doubly-linked-list-typed
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Doubly Linked List
1,207 lines • 51.5 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.DoublyLinkedList = exports.DoublyLinkedListNode = void 0;
const linear_base_1 = require("../base/linear-base");
class DoublyLinkedListNode extends linear_base_1.LinkedListNode {
/**
* The constructor function initializes the value, next, and previous properties of an object.
* @param {E} value - The "value" parameter is the value that will be stored in the node. It can be of any data type, as it
* is defined as a generic type "E".
*/
constructor(value) {
super(value);
this._value = value;
this._next = undefined;
this._prev = undefined;
}
get next() {
return this._next;
}
set next(value) {
this._next = value;
}
get prev() {
return this._prev;
}
set prev(value) {
this._prev = value;
}
}
exports.DoublyLinkedListNode = DoublyLinkedListNode;
/**
* 1. Node Structure: Each node contains three parts: a data field, a pointer (or reference) to the previous node, and a pointer to the next node. This structure allows traversal of the linked list in both directions.
* 2. Bidirectional Traversal: Unlike singly linked lists, doubly linked lists can be easily traversed forwards or backwards. This makes insertions and deletions in the list more flexible and efficient.
* 3. No Centralized Index: Unlike arrays, elements in a linked list are not stored contiguously, so there is no centralized index. Accessing elements in a linked list typically requires traversing from the head or tail node.
* 4. High Efficiency in Insertion and Deletion: Adding or removing elements in a linked list does not require moving other elements, making these operations more efficient than in arrays.
* Caution: Although our linked list classes provide methods such as at, setAt, addAt, and indexOf that are based on array indices, their time complexity, like that of the native Array.lastIndexOf, is 𝑂(𝑛). If you need to use these methods frequently, you might want to consider other data structures, such as Deque or Queue (designed for random access). Similarly, since the native Array.shift method has a time complexity of 𝑂(𝑛), using an array to simulate a queue can be inefficient. In such cases, you should use Queue or Deque, as these data structures leverage deferred array rearrangement, effectively reducing the average time complexity to 𝑂(1).
* @example
* // text editor operation history
* const actions = [
* { type: 'insert', content: 'first line of text' },
* { type: 'insert', content: 'second line of text' },
* { type: 'delete', content: 'delete the first line' }
* ];
* const editorHistory = new DoublyLinkedList<{ type: string; content: string }>(actions);
*
* console.log(editorHistory.last?.type); // 'delete'
* console.log(editorHistory.pop()?.content); // 'delete the first line'
* console.log(editorHistory.last?.type); // 'insert'
* @example
* // Browser history
* const browserHistory = new DoublyLinkedList<string>();
*
* browserHistory.push('home page');
* browserHistory.push('search page');
* browserHistory.push('details page');
*
* console.log(browserHistory.last); // 'details page'
* console.log(browserHistory.pop()); // 'details page'
* console.log(browserHistory.last); // 'search page'
* @example
* // Use DoublyLinkedList to implement music player
* // Define the Song interface
* interface Song {
* title: string;
* artist: string;
* duration: number; // duration in seconds
* }
*
* class Player {
* private playlist: DoublyLinkedList<Song>;
* private currentSong: ReturnType<typeof this.playlist.getNodeAt> | undefined;
*
* constructor(songs: Song[]) {
* this.playlist = new DoublyLinkedList<Song>();
* songs.forEach(song => this.playlist.push(song));
* this.currentSong = this.playlist.head;
* }
*
* // Play the next song in the playlist
* playNext(): Song | undefined {
* if (!this.currentSong?.next) {
* this.currentSong = this.playlist.head; // Loop to the first song
* } else {
* this.currentSong = this.currentSong.next;
* }
* return this.currentSong?.value;
* }
*
* // Play the previous song in the playlist
* playPrevious(): Song | undefined {
* if (!this.currentSong?.prev) {
* this.currentSong = this.playlist.tail; // Loop to the last song
* } else {
* this.currentSong = this.currentSong.prev;
* }
* return this.currentSong?.value;
* }
*
* // Get the current song
* getCurrentSong(): Song | undefined {
* return this.currentSong?.value;
* }
*
* // Loop through the playlist twice
* loopThroughPlaylist(): Song[] {
* const playedSongs: Song[] = [];
* const initialNode = this.currentSong;
*
* // Loop through the playlist twice
* for (let i = 0; i < this.playlist.length * 2; i++) {
* playedSongs.push(this.currentSong!.value);
* this.currentSong = this.currentSong!.next || this.playlist.head; // Loop back to the start if needed
* }
*
* // Reset the current song to the initial song
* this.currentSong = initialNode;
* return playedSongs;
* }
* }
*
* const songs = [
* { title: 'Bohemian Rhapsody', artist: 'Queen', duration: 354 },
* { title: 'Hotel California', artist: 'Eagles', duration: 391 },
* { title: 'Shape of You', artist: 'Ed Sheeran', duration: 233 },
* { title: 'Billie Jean', artist: 'Michael Jackson', duration: 294 }
* ];
* let player = new Player(songs);
* // should play the next song
* player = new Player(songs);
* const firstSong = player.getCurrentSong();
* const nextSong = player.playNext();
*
* // Expect the next song to be "Hotel California by Eagles"
* console.log(nextSong); // { title: 'Hotel California', artist: 'Eagles', duration: 391 }
* console.log(firstSong); // { title: 'Bohemian Rhapsody', artist: 'Queen', duration: 354 }
*
* // should play the previous song
* player = new Player(songs);
* player.playNext(); // Move to the second song
* const currentSong = player.getCurrentSong();
* const previousSong = player.playPrevious();
*
* // Expect the previous song to be "Bohemian Rhapsody by Queen"
* console.log(previousSong); // { title: 'Bohemian Rhapsody', artist: 'Queen', duration: 354 }
* console.log(currentSong); // { title: 'Hotel California', artist: 'Eagles', duration: 391 }
*
* // should loop to the first song when playing next from the last song
* player = new Player(songs);
* player.playNext(); // Move to the second song
* player.playNext(); // Move to the third song
* player.playNext(); // Move to the fourth song
*
* const nextSongToFirst = player.playNext(); // Should loop to the first song
*
* // Expect the next song to be "Bohemian Rhapsody by Queen"
* console.log(nextSongToFirst); // { title: 'Bohemian Rhapsody', artist: 'Queen', duration: 354 }
*
* // should loop to the last song when playing previous from the first song
* player = new Player(songs);
* player.playNext(); // Move to the first song
* player.playNext(); // Move to the second song
* player.playNext(); // Move to the third song
* player.playNext(); // Move to the fourth song
*
* const previousToLast = player.playPrevious(); // Should loop to the last song
*
* // Expect the previous song to be "Billie Jean by Michael Jackson"
* console.log(previousToLast); // { title: 'Billie Jean', artist: 'Michael Jackson', duration: 294 }
*
* // should loop through the entire playlist
* player = new Player(songs);
* const playedSongs = player.loopThroughPlaylist();
*
* // The expected order of songs for two loops
* console.log(playedSongs); // [
* // { title: 'Bohemian Rhapsody', artist: 'Queen', duration: 354 },
* // { title: 'Hotel California', artist: 'Eagles', duration: 391 },
* // { title: 'Shape of You', artist: 'Ed Sheeran', duration: 233 },
* // { title: 'Billie Jean', artist: 'Michael Jackson', duration: 294 },
* // { title: 'Bohemian Rhapsody', artist: 'Queen', duration: 354 },
* // { title: 'Hotel California', artist: 'Eagles', duration: 391 },
* // { title: 'Shape of You', artist: 'Ed Sheeran', duration: 233 },
* // { title: 'Billie Jean', artist: 'Michael Jackson', duration: 294 }
* // ]
* @example
* // Use DoublyLinkedList to implement LRU cache
* interface CacheEntry<K, V> {
* key: K;
* value: V;
* }
*
* class LRUCache<K = string, V = any> {
* private readonly capacity: number;
* private list: DoublyLinkedList<CacheEntry<K, V>>;
* private map: Map<K, DoublyLinkedListNode<CacheEntry<K, V>>>;
*
* constructor(capacity: number) {
* if (capacity <= 0) {
* throw new Error('lru cache capacity must be greater than 0');
* }
* this.capacity = capacity;
* this.list = new DoublyLinkedList<CacheEntry<K, V>>();
* this.map = new Map<K, DoublyLinkedListNode<CacheEntry<K, V>>>();
* }
*
* // Get cached value
* get(key: K): V | undefined {
* const node = this.map.get(key);
*
* if (!node) return undefined;
*
* // Move the visited node to the head of the linked list (most recently used)
* this.moveToFront(node);
*
* return node.value.value;
* }
*
* // Set cache value
* set(key: K, value: V): void {
* // Check if it already exists
* const node = this.map.get(key);
*
* if (node) {
* // Update value and move to head
* node.value.value = value;
* this.moveToFront(node);
* return;
* }
*
* // Check capacity
* if (this.list.length >= this.capacity) {
* // Delete the least recently used element (the tail of the linked list)
* const removedNode = this.list.tail;
* if (removedNode) {
* this.map.delete(removedNode.value.key);
* this.list.pop();
* }
* }
*
* // Create new node and add to head
* const newEntry: CacheEntry<K, V> = { key, value };
* this.list.unshift(newEntry);
*
* // Save node reference in map
* const newNode = this.list.head;
* if (newNode) {
* this.map.set(key, newNode);
* }
* }
*
* // Move the node to the head of the linked list
* private moveToFront(node: DoublyLinkedListNode<CacheEntry<K, V>>): void {
* this.list.delete(node);
* this.list.unshift(node.value);
* }
*
* // Delete specific key
* delete(key: K): boolean {
* const node = this.map.get(key);
* if (!node) return false;
*
* // Remove from linked list
* this.list.delete(node);
* // Remove from map
* this.map.delete(key);
*
* return true;
* }
*
* // Clear cache
* clear(): void {
* this.list.clear();
* this.map.clear();
* }
*
* // Get the current cache length
* get length(): number {
* return this.list.length;
* }
*
* // Check if it is empty
* get isEmpty(): boolean {
* return this.list.isEmpty();
* }
* }
*
* // should set and get values correctly
* const cache = new LRUCache<string, number>(3);
* cache.set('a', 1);
* cache.set('b', 2);
* cache.set('c', 3);
*
* console.log(cache.get('a')); // 1
* console.log(cache.get('b')); // 2
* console.log(cache.get('c')); // 3
*
* // The least recently used element should be evicted when capacity is exceeded
* cache.clear();
* cache.set('a', 1);
* cache.set('b', 2);
* cache.set('c', 3);
* cache.set('d', 4); // This will eliminate 'a'
*
* console.log(cache.get('a')); // undefined
* console.log(cache.get('b')); // 2
* console.log(cache.get('c')); // 3
* console.log(cache.get('d')); // 4
*
* // The priority of an element should be updated when it is accessed
* cache.clear();
* cache.set('a', 1);
* cache.set('b', 2);
* cache.set('c', 3);
*
* cache.get('a'); // access 'a'
* cache.set('d', 4); // This will eliminate 'b'
*
* console.log(cache.get('a')); // 1
* console.log(cache.get('b')); // undefined
* console.log(cache.get('c')); // 3
* console.log(cache.get('d')); // 4
*
* // Should support updating existing keys
* cache.clear();
* cache.set('a', 1);
* cache.set('a', 10);
*
* console.log(cache.get('a')); // 10
*
* // Should support deleting specified keys
* cache.clear();
* cache.set('a', 1);
* cache.set('b', 2);
*
* console.log(cache.delete('a')); // true
* console.log(cache.get('a')); // undefined
* console.log(cache.length); // 1
*
* // Should support clearing cache
* cache.clear();
* cache.set('a', 1);
* cache.set('b', 2);
* cache.clear();
*
* console.log(cache.length); // 0
* console.log(cache.isEmpty); // true
* @example
* // finding lyrics by timestamp in Coldplay's "Fix You"
* // Create a DoublyLinkedList to store song lyrics with timestamps
* const lyricsList = new DoublyLinkedList<{ time: number; text: string }>();
*
* // Detailed lyrics with precise timestamps (in milliseconds)
* const lyrics = [
* { time: 0, text: "When you try your best, but you don't succeed" },
* { time: 4000, text: 'When you get what you want, but not what you need' },
* { time: 8000, text: "When you feel so tired, but you can't sleep" },
* { time: 12000, text: 'Stuck in reverse' },
* { time: 16000, text: 'And the tears come streaming down your face' },
* { time: 20000, text: "When you lose something you can't replace" },
* { time: 24000, text: 'When you love someone, but it goes to waste' },
* { time: 28000, text: 'Could it be worse?' },
* { time: 32000, text: 'Lights will guide you home' },
* { time: 36000, text: 'And ignite your bones' },
* { time: 40000, text: 'And I will try to fix you' }
* ];
*
* // Populate the DoublyLinkedList with lyrics
* lyrics.forEach(lyric => lyricsList.push(lyric));
*
* // Test different scenarios of lyric synchronization
*
* // 1. Find lyric at exact timestamp
* const exactTimeLyric = lyricsList.getBackward(lyric => lyric.value.time <= 36000);
* console.log(exactTimeLyric?.text); // 'And ignite your bones'
*
* // 2. Find lyric between timestamps
* const betweenTimeLyric = lyricsList.getBackward(lyric => lyric.value.time <= 22000);
* console.log(betweenTimeLyric?.text); // "When you lose something you can't replace"
*
* // 3. Find first lyric when timestamp is less than first entry
* const earlyTimeLyric = lyricsList.getBackward(lyric => lyric.value.time <= -1000);
* console.log(earlyTimeLyric); // undefined
*
* // 4. Find last lyric when timestamp is after last entry
* const lateTimeLyric = lyricsList.getBackward(lyric => lyric.value.time <= 50000);
* console.log(lateTimeLyric?.text); // 'And I will try to fix you'
* @example
* // cpu process schedules
* class Process {
* constructor(
* public id: number,
* public priority: number
* ) {}
*
* execute(): string {
* return `Process ${this.id} executed.`;
* }
* }
*
* class Scheduler {
* private queue: DoublyLinkedList<Process>;
*
* constructor() {
* this.queue = new DoublyLinkedList<Process>();
* }
*
* addProcess(process: Process): void {
* // Insert processes into a queue based on priority, keeping priority in descending order
* let current = this.queue.head;
* while (current && current.value.priority >= process.priority) {
* current = current.next;
* }
*
* if (!current) {
* this.queue.push(process);
* } else {
* this.queue.addBefore(current, process);
* }
* }
*
* executeNext(): string | undefined {
* // Execute tasks at the head of the queue in order
* const process = this.queue.shift();
* return process ? process.execute() : undefined;
* }
*
* listProcesses(): string[] {
* return this.queue.toArray().map(process => `Process ${process.id} (Priority: ${process.priority})`);
* }
*
* clear(): void {
* this.queue.clear();
* }
* }
*
* // should add processes based on priority
* let scheduler = new Scheduler();
* scheduler.addProcess(new Process(1, 10));
* scheduler.addProcess(new Process(2, 20));
* scheduler.addProcess(new Process(3, 15));
*
* console.log(scheduler.listProcesses()); // [
* // 'Process 2 (Priority: 20)',
* // 'Process 3 (Priority: 15)',
* // 'Process 1 (Priority: 10)'
* // ]
*
* // should execute the highest priority process
* scheduler = new Scheduler();
* scheduler.addProcess(new Process(1, 10));
* scheduler.addProcess(new Process(2, 20));
*
* console.log(scheduler.executeNext()); // 'Process 2 executed.'
* console.log(scheduler.listProcesses()); // ['Process 1 (Priority: 10)']
*
* // should clear all processes
* scheduler = new Scheduler();
* scheduler.addProcess(new Process(1, 10));
* scheduler.addProcess(new Process(2, 20));
*
* scheduler.clear();
* console.log(scheduler.listProcesses()); // []
*/
class DoublyLinkedList extends linear_base_1.LinearLinkedBase {
/**
* This TypeScript constructor initializes a DoublyLinkedList with optional elements and options.
* @param {Iterable<E> | Iterable<R>} elements - The `elements` parameter in the constructor is an
* iterable collection of elements of type `E` or `R`. It is used to initialize the DoublyLinkedList
* with the elements provided in the iterable. If no elements are provided, the default value is an
* empty iterable.
* @param [options] - The `options` parameter in the constructor is of type
* `DoublyLinkedListOptions<E, R>`. It is an optional parameter that allows you to pass additional
* configuration options to customize the behavior of the DoublyLinkedList.
*/
constructor(elements = [], options) {
super(options);
this._head = undefined;
this._tail = undefined;
this._length = 0;
if (options) {
const { maxLen } = options;
if (typeof maxLen === 'number' && maxLen > 0 && maxLen % 1 === 0)
this._maxLen = maxLen;
}
this.pushMany(elements);
}
get head() {
return this._head;
}
get tail() {
return this._tail;
}
get length() {
return this._length;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The `get first` function returns the first node in a doubly linked list, or undefined if the list is empty.
* @returns The method `get first()` returns the first node of the doubly linked list, or `undefined` if the list is empty.
*/
get first() {
var _a;
return (_a = this.head) === null || _a === void 0 ? void 0 : _a.value;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The `get last` function returns the last node in a doubly linked list, or undefined if the list is empty.
* @returns The method `get last()` returns the last node of the doubly linked list, or `undefined` if the list is empty.
*/
get last() {
var _a;
return (_a = this.tail) === null || _a === void 0 ? void 0 : _a.value;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(n)
*
* The `fromArray` function creates a new instance of a DoublyLinkedList and populates it with the elements from the
* given array.
* @param {E[]} data - The `data` parameter is an array of elements of type `E`.
* @returns The `fromArray` function returns a DoublyLinkedList object.
*/
static fromArray(data) {
return new DoublyLinkedList(data);
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The function `isNode` in TypeScript checks if a given input is an instance of
* `DoublyLinkedListNode`.
* @param {E | DoublyLinkedListNode<E> | ((node: DoublyLinkedListNode<E>) => boolean)} elementNodeOrPredicate
* elementNodeOrPredicate - The `elementNodeOrPredicate` parameter in the `isNode` function can
* be one of the following types:
* @returns The `isNode` function is checking if the `elementNodeOrPredicate` parameter is an
* instance of `DoublyLinkedListNode<E>`. If it is, the function returns `true`, indicating that the
* parameter is a `DoublyLinkedListNode<E>`. If it is not an instance of `DoublyLinkedListNode<E>`,
* the function returns `false`.
*/
isNode(elementNodeOrPredicate) {
return elementNodeOrPredicate instanceof DoublyLinkedListNode;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The `push` function adds a new element or node to the end of a doubly linked list.
* @param {E | DoublyLinkedListNode<E>} elementOrNode - The `elementOrNode` parameter in the `push`
* method can accept either an element of type `E` or a `DoublyLinkedListNode<E>` object.
* @returns The `push` method is returning a boolean value, specifically `true`.
*/
push(elementOrNode) {
const newNode = this._ensureNode(elementOrNode);
if (!this.head) {
this._head = newNode;
this._tail = newNode;
}
else {
newNode.prev = this.tail;
this.tail.next = newNode;
this._tail = newNode;
}
this._length++;
if (this._maxLen > 0 && this.length > this._maxLen)
this.shift();
return true;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The `pop()` function removes and returns the value of the last element in a linked list.
* @returns The method is returning the value of the removed node.
*/
pop() {
if (!this.tail)
return undefined;
const removedNode = this.tail;
if (this.head === this.tail) {
this._head = undefined;
this._tail = undefined;
}
else {
this._tail = removedNode.prev;
this.tail.next = undefined;
}
this._length--;
return removedNode.value;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The `shift()` function removes and returns the value of the first element in a doubly linked list.
* @returns The value of the removed node.
*/
shift() {
if (!this.head)
return undefined;
const removedNode = this.head;
if (this.head === this.tail) {
this._head = undefined;
this._tail = undefined;
}
else {
this._head = removedNode.next;
this.head.prev = undefined;
}
this._length--;
return removedNode.value;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The unshift function adds a new element or node to the beginning of a doubly linked list.
* @param {E | DoublyLinkedListNode<E>} elementOrNode - The `elementOrNode` parameter in the
* `unshift` method can be either an element of type `E` or a `DoublyLinkedListNode` containing an
* element of type `E`.
* @returns The `unshift` method is returning a boolean value, specifically `true`.
*/
unshift(elementOrNode) {
const newNode = this._ensureNode(elementOrNode);
if (!this.head) {
this._head = newNode;
this._tail = newNode;
}
else {
newNode.next = this.head;
this.head.prev = newNode;
this._head = newNode;
}
this._length++;
if (this._maxLen > 0 && this._length > this._maxLen)
this.pop();
return true;
}
/**
* Time Complexity: O(k)
* Space Complexity: O(k)
*
* The function `pushMany` iterates over elements and pushes them into a data structure, applying a
* transformation function if provided.
* @param {Iterable<E> | Iterable<R> | Iterable<DoublyLinkedListNode<E>>} elements - The `elements`
* parameter in the `pushMany` function can accept an iterable containing elements of type `E`, `R`,
* or `DoublyLinkedListNode<E>`. The function iterates over each element in the iterable and pushes
* it onto the linked list. If a transformation function `to
* @returns The `pushMany` function is returning an array of boolean values (`ans`) which indicate
* the success or failure of pushing each element into the data structure.
*/
pushMany(elements) {
const ans = [];
for (const el of elements) {
if (this.toElementFn) {
ans.push(this.push(this.toElementFn(el)));
continue;
}
ans.push(this.push(el));
}
return ans;
}
/**
* Time Complexity: O(k)
* Space Complexity: O(k)
*
* The function `unshiftMany` iterates through a collection of elements and adds them to the
* beginning of a Doubly Linked List, returning an array of boolean values indicating the success of
* each insertion.
* @param {Iterable<E> | Iterable<R> | Iterable<DoublyLinkedListNode<E>>} elements - The `elements`
* parameter in the `unshiftMany` function can accept an iterable containing elements of type `E`,
* `R`, or `DoublyLinkedListNode<E>`. The function iterates over each element in the iterable and
* performs an `unshift` operation on the doubly linked list
* @returns The `unshiftMany` function returns an array of boolean values indicating the success of
* each unshift operation performed on the elements passed as input.
*/
unshiftMany(elements) {
const ans = [];
for (const el of elements) {
if (this.toElementFn) {
ans.push(this.unshift(this.toElementFn(el)));
continue;
}
ans.push(this.unshift(el));
}
return ans;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The `at` function returns the value at a specified index in a linked list, or undefined if the index is out of bounds.
* @param {number} index - The index parameter is a number that represents the position of the element we want to
* retrieve from the list.
* @returns The method is returning the value at the specified index in the linked list. If the index is out of bounds
* or the linked list is empty, it will return undefined.
*/
at(index) {
if (index < 0 || index >= this._length)
return undefined;
let current = this.head;
for (let i = 0; i < index; i++) {
current = current.next;
}
return current.value;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The function `getNodeAt` returns the node at a given index in a doubly linked list, or undefined if the index is out of
* range.
* @param {number} index - The `index` parameter is a number that represents the position of the node we want to
* retrieve from the doubly linked list. It indicates the zero-based index of the node we want to access.
* @returns The method `getNodeAt(index: number)` returns a `DoublyLinkedListNode<E>` object if the index is within the
* valid range of the linked list, otherwise it returns `undefined`.
*/
getNodeAt(index) {
if (index < 0 || index >= this._length)
return undefined;
let current = this.head;
for (let i = 0; i < index; i++) {
current = current.next;
}
return current;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* This TypeScript function searches for a node in a doubly linked list based on a given element node
* or predicate.
* @param {| E
* | DoublyLinkedListNode<E>
* | ((node: DoublyLinkedListNode<E>) => boolean)
* | undefined} elementNodeOrPredicate - The `getNode` method you provided is used to find a
* node in a doubly linked list based on a given element, node, or predicate function. The
* `elementNodeOrPredicate` parameter can be one of the following:
* @returns The `getNode` method returns a `DoublyLinkedListNode<E>` or `undefined` based on the
* input `elementNodeOrPredicate`. If the input is `undefined`, the method returns `undefined`.
* Otherwise, it iterates through the linked list starting from the head node and applies the
* provided predicate function to each node. If a node satisfies the predicate, that node is
* returned. If
*/
getNode(elementNodeOrPredicate) {
if (elementNodeOrPredicate === undefined)
return;
if (this.isNode(elementNodeOrPredicate))
return elementNodeOrPredicate;
const predicate = this._ensurePredicate(elementNodeOrPredicate);
let current = this.head;
while (current) {
if (predicate(current)) {
return current;
}
current = current.next;
}
return undefined;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The `addAt` function inserts a new element or node at a specified index in a doubly linked list.
* @param {number} index - The `index` parameter in the `addAt` method represents the position at
* which you want to add a new element or node in the doubly linked list. It indicates the location
* where the new element or node should be inserted.
* @param {E | DoublyLinkedListNode<E>} newElementOrNode - The `newElementOrNode` parameter in the
* `addAt` method can be either a value of type `E` or a `DoublyLinkedListNode<E>` object.
* @returns The `addAt` method returns a boolean value. It returns `true` if the element or node was
* successfully added at the specified index, and `false` if the index is out of bounds (less than 0
* or greater than the length of the list).
*/
addAt(index, newElementOrNode) {
if (index < 0 || index > this._length)
return false;
if (index === 0) {
this.unshift(newElementOrNode);
return true;
}
if (index === this._length) {
this.push(newElementOrNode);
return true;
}
const newNode = this._ensureNode(newElementOrNode);
const prevNode = this.getNodeAt(index - 1);
const nextNode = prevNode.next;
newNode.prev = prevNode;
newNode.next = nextNode;
prevNode.next = newNode;
nextNode.prev = newNode;
this._length++;
return true;
}
/**
* Time Complexity: O(1) or O(n)
* Space Complexity: O(1)
*
* The `addBefore` function in TypeScript adds a new element or node before an existing element or
* node in a doubly linked list.
* @param {E | DoublyLinkedListNode<E>} existingElementOrNode - The `existingElementOrNode` parameter
* in the `addBefore` method can be either an element of type `E` or a `DoublyLinkedListNode<E>`.
* @param {E | DoublyLinkedListNode<E>} newElementOrNode - The `newElementOrNode` parameter
* represents the element or node that you want to add before the `existingElementOrNode` in a doubly
* linked list.
* @returns The `addBefore` method returns a boolean value - `true` if the new element or node was
* successfully added before the existing element or node, and `false` if the existing element or
* node was not found.
*/
addBefore(existingElementOrNode, newElementOrNode) {
const existingNode = this.isNode(existingElementOrNode)
? existingElementOrNode
: this.getNode(existingElementOrNode);
if (existingNode) {
const newNode = this._ensureNode(newElementOrNode);
newNode.prev = existingNode.prev;
if (existingNode.prev) {
existingNode.prev.next = newNode;
}
newNode.next = existingNode;
existingNode.prev = newNode;
if (existingNode === this.head) {
this._head = newNode;
}
this._length++;
return true;
}
return false;
}
/**
* Time Complexity: O(1) or O(n)
* Space Complexity: O(1)
*
* The `addAfter` function in TypeScript adds a new element or node after an existing element or node
* in a doubly linked list.
* @param {E | DoublyLinkedListNode<E>} existingElementOrNode - existingElementOrNode represents the
* element or node in the doubly linked list after which you want to add a new element or node.
* @param {E | DoublyLinkedListNode<E>} newElementOrNode - The `newElementOrNode` parameter in the
* `addAfter` method represents the element or node that you want to add after the existing element
* or node in a doubly linked list. This parameter can be either an element value or a
* `DoublyLinkedListNode` object that you want to insert
* @returns The `addAfter` method returns a boolean value - `true` if the new element or node was
* successfully added after the existing element or node, and `false` if the existing element or node
* was not found in the linked list.
*/
addAfter(existingElementOrNode, newElementOrNode) {
const existingNode = this.isNode(existingElementOrNode)
? existingElementOrNode
: this.getNode(existingElementOrNode);
if (existingNode) {
const newNode = this._ensureNode(newElementOrNode);
newNode.next = existingNode.next;
if (existingNode.next) {
existingNode.next.prev = newNode;
}
newNode.prev = existingNode;
existingNode.next = newNode;
if (existingNode === this.tail) {
this._tail = newNode;
}
this._length++;
return true;
}
return false;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The function `setAt` updates the value at a specified index in a data structure if the index
* exists.
* @param {number} index - The `index` parameter in the `setAt` method refers to the position in the
* data structure where you want to set a new value.
* @param {E} value - The `value` parameter in the `setAt` method represents the new value that you
* want to set at the specified index in the data structure.
* @returns The `setAt` method returns a boolean value - `true` if the value at the specified index
* is successfully updated, and `false` if the index is out of bounds.
*/
setAt(index, value) {
const node = this.getNodeAt(index);
if (node) {
node.value = value;
return true;
}
return false;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The `deleteAt` function removes an element at a specified index from a linked list and returns the removed element.
* @param {number} index - The index parameter represents the position of the element that needs to be deleted in the
* data structure. It is of type number.
* @returns The method `deleteAt` returns the value of the node that was deleted, or `undefined` if the index is out of
* bounds.
*/
deleteAt(index) {
if (index < 0 || index >= this._length)
return;
let deleted;
if (index === 0) {
deleted = this.first;
this.shift();
return deleted;
}
if (index === this._length - 1) {
deleted = this.last;
this.pop();
return deleted;
}
const removedNode = this.getNodeAt(index);
const prevNode = removedNode.prev;
const nextNode = removedNode.next;
prevNode.next = nextNode;
nextNode.prev = prevNode;
this._length--;
return removedNode === null || removedNode === void 0 ? void 0 : removedNode.value;
}
/**
* Time Complexity: O(1) or O(n)
* Space Complexity: O(1)
*
* The `delete` function removes a specified element or node from a doubly linked list if it exists.
* @param {E | DoublyLinkedListNode<E> | undefined} elementOrNode - The `elementOrNode` parameter in
* the `delete` method can accept an element of type `E`, a `DoublyLinkedListNode` of type `E`, or it
* can be `undefined`. This parameter is used to identify the node that needs to be deleted from the
* doubly linked list
* @returns The `delete` method returns a boolean value - `true` if the element or node was
* successfully deleted from the doubly linked list, and `false` if the element or node was not found
* in the list.
*/
delete(elementOrNode) {
const node = this.getNode(elementOrNode);
if (node) {
if (node === this.head) {
this.shift();
}
else if (node === this.tail) {
this.pop();
}
else {
const prevNode = node.prev;
const nextNode = node.next;
if (prevNode)
prevNode.next = nextNode;
if (nextNode)
nextNode.prev = prevNode;
this._length--;
}
return true;
}
return false;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The function checks if a variable has a length greater than zero and returns a boolean value.
* @returns A boolean value is being returned.
*/
isEmpty() {
return this._length === 0;
}
/**
* Time Complexity: O(1)
* Space Complexity: O(1)
*
* The `clear` function resets the linked list by setting the head, tail, and length to undefined and 0 respectively.
*/
clear() {
this._head = undefined;
this._tail = undefined;
this._length = 0;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* This function retrieves an element from a doubly linked list based on a given element
* node or predicate.
* @param {E | DoublyLinkedListNode<E> | ((node: DoublyLinkedListNode<E>) => boolean)} elementNodeOrPredicate
* elementNodeOrPredicate - The `get` method takes in a parameter called `elementNodeOrPredicate`,
* which can be one of the following types:
* @returns The `get` method returns the value of the first node in the doubly linked list that
* satisfies the provided predicate function. If no such node is found, it returns `undefined`.
*/
search(elementNodeOrPredicate) {
const predicate = this._ensurePredicate(elementNodeOrPredicate);
let current = this.head;
while (current) {
if (predicate(current))
return current.value;
current = current.next;
}
return undefined;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The `getBackward` function searches for a specific element in a doubly linked list starting from
* the tail and moving backwards.
* @param {E | DoublyLinkedListNode<E> | ((node: DoublyLinkedListNode<E>) => boolean)} elementNodeOrPredicate
* elementNodeOrPredicate - The `elementNodeOrPredicate` parameter in the `getBackward`
* function can be one of the following types:
* @returns The `getBackward` method returns the value of the element node that matches the provided
* predicate when traversing the doubly linked list backwards. If no matching element is found, it
* returns `undefined`.
*/
getBackward(elementNodeOrPredicate) {
const predicate = this._ensurePredicate(elementNodeOrPredicate);
let current = this.tail;
while (current) {
if (predicate(current))
return current.value;
current = current.prev;
}
return undefined;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The `reverse` function reverses the order of the elements in a doubly linked list.
*/
reverse() {
let current = this.head;
[this._head, this._tail] = [this.tail, this.head];
while (current) {
const next = current.next;
[current.prev, current.next] = [current.next, current.prev];
current = next;
}
return this;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(n)
*
* The `clone` function creates a new instance of the `DoublyLinkedList` class with the same values
* as the original list.
* @returns The `clone()` method is returning a new instance of the `DoublyLinkedList` class, which
* is a copy of the original list.
*/
clone() {
return new DoublyLinkedList(this, { toElementFn: this._toElementFn, maxLen: this._maxLen });
}
/**
* Time Complexity: O(n)
* Space Complexity: O(n)
*
* The `filter` function creates a new DoublyLinkedList by iterating over the elements of the current
* list and applying a callback function to each element, returning only the elements for which the
* callback function returns true.
* @param callback - The `callback` parameter is a function that will be called for each element in
* the DoublyLinkedList. It takes three arguments: the current element, the index of the current
* element, and the DoublyLinkedList itself. The callback function should return a boolean value
* indicating whether the current element should be included
* @param {any} [thisArg] - The `thisArg` parameter is an optional argument that specifies the value
* to be used as `this` when executing the `callback` function. If `thisArg` is provided, it will be
* passed as the `this` value to the `callback` function. If `thisArg` is
* @returns The `filter` method is returning a new `DoublyLinkedList` object that contains the
* elements that pass the filter condition specified by the `callback` function.
*/
filter(callback, thisArg) {
const filteredList = this._createInstance({ toElementFn: this.toElementFn, maxLen: this._maxLen });
let index = 0;
for (const current of this) {
if (callback.call(thisArg, current, index, this)) {
filteredList.push(current);
}
index++;
}
return filteredList;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(n)
*
* The `map` function takes a callback function and returns a new DoublyLinkedList with the results
* of applying the callback to each element in the original list.
* @param callback - The callback parameter is a function that will be called for each element in the
* original DoublyLinkedList. It takes three arguments: current (the current element being
* processed), index (the index of the current element), and this (the original DoublyLinkedList).
* The callback function should return a value of type
* @param [toElementFn] - The `toElementFn` parameter is an optional function that can be used to
* convert the raw element (`RR`) to the desired element type (`T`). It takes the raw element as
* input and returns the converted element. If this parameter is not provided, the raw element will
* be used as is.
* @param {any} [thisArg] - The `thisArg` parameter is an optional argument that allows you to
* specify the value of `this` within the callback function. It is used to set the context or scope
* in which the callback function will be executed. If `thisArg` is provided, it will be used as the
* value of
* @returns a new instance of the `DoublyLinkedList` class with elements of type `T` and `RR`.
*/
map(callback, toElementFn, thisArg) {
const mappedList = new DoublyLinkedList([], { toElementFn, maxLen: this._maxLen });
let index = 0;
for (const current of this) {
mappedList.push(callback.call(thisArg, current, index, this));
index++;
}
return mappedList;
}
/**
* Time Complexity: O(n)
* Space Complexity: O(1)
*
* The function `countOccurrences` iterates through a doubly linked list and counts the occurrences
* of a specified element or nodes that satisfy a given predicate.
* @param {E | DoublyLinkedListNode<E> | ((node: DoublyLinkedListNode<E>) => boolean)} elementOrNode
* - The `elementOrNode` parameter in the `countOccurrences` method can accept three types of values:
* @returns The `countOccurrences` method returns the number of occurrences of the specified element,
* node, or predicate function in the doubly linked list.
*/
countOccurrences(elementOrNode) {
const predicate = this._ensurePredicate(elementOrNode);
let count = 0;
let current = this.head;
while (current) {
if (predicate(current)) {
count++;
}
current = current.next;
}
return count;
}
/**
* The function returns an iterator that iterates over the values of a linked list.
*/
*_getIterator() {
let current = this.head;
while (current) {
yield current.value;
current = current.next;
}
}
/**
* The function returns an iterator that iterates over the elements of a data structure in reverse
* order.
*/
*_getReverseIterator() {
let current = this.tail;
while (current) {
yield current.value;
current = current.prev;
}
}
/**
* The function returns an iterator that iterates over the nodes of a doubly linked list starting
* from the head.
*/
*_getNodeIterator() {
let current = this.head;
while (current) {
yield current;
current = current.next;
}
}
// protected *_getReverseNodeIterator(): IterableIterator<DoublyLinkedListNode<E>> {
// const reversedArr = [...this._getNodeIterator()].reverse();
//
// for (const item of reversedArr) {
// yield item;
// }
// }
/**
* The function `_isPredicate` checks if the input is a function that takes a `DoublyLinkedListNode`
* as an argument and returns a boolean.
* @param {E | DoublyLinkedListNode<E> | ((node: DoublyLinkedListNode<E>) => boolean)} elementNodeOrPredicate
* elementNodeOrPredicate - The `elementNodeOrPredicate` parameter can be one of the following
* types:
* @returns The _isPredicate method is returning a boolean value indicating whether the
* elementNodeOrPredicate parameter is a function or not. If the elementNodeOrPredicate is a
* function, the method will return true, indicating that it is a predicate function.
*/
_isPredicate(elementNodeOrPredicate) {
return typeof elementNodeOrPredicate === 'function';
}
/**
* The function `_ensureNode` ensures that the input is a valid node in a doubly linked list.
* @param {E | DoublyLinkedListNode<E>} elementOrNode - The `elementOrNode` parameter can be either
* an element of type `E` or a `DoublyLinkedListNode` containing an element of type `E`.
* @returns If the `elementOrNode` parameter is already a `DoublyLinkedListNode`, it will be returned
* as is. Otherwise, a new `DoublyLinkedListNode` instance will be created with the `elementOrNode`
* value and returned.
*/
_ensureNode(elementOrNode) {
if (this.isNode(elementOrNode))
return elementOrNode;
return new DoublyLinkedListNode(elementOrNode);
}
/**
* The function `_ensurePredicate` in TypeScript ensures that the input is either a node, a predicate
* function, or a value to compare with the node's value.
* @param {E | DoublyLinkedListNode<E> | ((node: DoublyLinkedListNode<E>) => boolean)} elementNodeOrPredicate
* elementNodeOrPredicate - The `elementNodeOrPredicate` parameter can be one of the following
* types:
* @returns A function is being returned that takes a `DoublyLinkedListNode` as a parameter and
* returns a boolean value based on the conditions specified in the code.
*/
_ensurePredicate(elementNodeOrPredicate) {
if (this.isNode(elementNodeOrPredicate))
return (node) => node === e