lgrthms/lib/algorithms/search/binarySearch.js

Algorithms and data structures for your JavaScript and TypeScript projects 🧑‍💻

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.searchForRange = exports.binarySearchLastIndex = exports.binarySearchLast = exports.binarySearchFirstIndex = exports.binarySearchFirst = exports.shiftedBinarySearchIndex = exports.shiftedBinarySearch = exports.binarySearchIndex = exports.binarySearch = void 0;
function binarySearch(array, target, get) {
    const index = binarySearchIndex(array, target, get);
    return index !== -1 ? array[index] : undefined;
}
exports.binarySearch = binarySearch;
function binarySearchIndex(array, target, get) {
    let leftIdx = 0;
    let rightIdx = array.length - 1;
    get = get ? get : (element) => element;
    while (leftIdx <= rightIdx) {
        const middleIdx = Math.floor((leftIdx + rightIdx) / 2);
        const element = array[middleIdx];
        const value = get(element);
        if (target === value) {
            return middleIdx;
        }
        if (target < value) {
            rightIdx = middleIdx - 1;
        }
        else {
            leftIdx = middleIdx + 1;
        }
    }
    return -1;
}
exports.binarySearchIndex = binarySearchIndex;
function shiftedBinarySearch(array, target, get) {
    const index = shiftedBinarySearchIndex(array, target, get);
    return index !== -1 ? array[index] : undefined;
}
exports.shiftedBinarySearch = shiftedBinarySearch;
function shiftedBinarySearchIndex(array, target, get) {
    let leftIdx = 0;
    let rightIdx = array.length - 1;
    get = get ? get : (element) => element;
    while (leftIdx <= rightIdx) {
        const middleIdx = Math.floor((leftIdx + rightIdx) / 2);
        const middleValue = get(array[middleIdx]);
        if (target === middleValue) {
            return middleIdx;
        }
        const leftValue = get(array[leftIdx]);
        const rightValue = get(array[rightIdx]);
        if (leftValue <= middleValue) {
            if (target < middleValue && target >= leftValue) {
                rightIdx = middleIdx - 1;
            }
            else {
                leftIdx = middleIdx + 1;
            }
        }
        else {
            if (target > middleValue && target <= rightValue) {
                leftIdx = middleIdx + 1;
            }
            else {
                rightIdx = middleIdx - 1;
            }
        }
    }
    return -1;
}
exports.shiftedBinarySearchIndex = shiftedBinarySearchIndex;
function binarySearchFirst(array, target, get) {
    const index = binarySearchFirstIndex(array, target, get);
    return index !== -1 ? array[index] : undefined;
}
exports.binarySearchFirst = binarySearchFirst;
function binarySearchFirstIndex(array, target, get) {
    let leftIdx = 0;
    let rightIdx = array.length - 1;
    get = get ? get : (element) => element;
    while (leftIdx <= rightIdx) {
        const middleIdx = Math.floor((leftIdx + rightIdx) / 2);
        const middleValue = get(array[middleIdx]);
        if (target === middleValue) {
            if (middleIdx === 0) {
                return middleIdx;
            }
            const middlePreviousValue = get(array[middleIdx - 1]);
            if (target === middlePreviousValue) {
                rightIdx = middleIdx - 1;
            }
            else {
                return middleIdx;
            }
        }
        if (target < middleValue) {
            rightIdx = middleIdx - 1;
        }
        else {
            leftIdx = middleIdx + 1;
        }
    }
    return -1;
}
exports.binarySearchFirstIndex = binarySearchFirstIndex;
function binarySearchLast(array, target, get) {
    const index = binarySearchLastIndex(array, target, get);
    return index !== -1 ? array[index] : undefined;
}
exports.binarySearchLast = binarySearchLast;
function binarySearchLastIndex(array, target, get) {
    let leftIdx = 0;
    let rightIdx = array.length - 1;
    get = get ? get : (element) => element;
    while (leftIdx <= rightIdx) {
        const middleIdx = Math.floor((leftIdx + rightIdx) / 2);
        const middleValue = get(array[middleIdx]);
        if (target === middleValue) {
            if (middleIdx === array.length - 1) {
                return middleIdx;
            }
            const middleNextValue = get(array[middleIdx + 1]);
            if (target === middleNextValue) {
                leftIdx = middleIdx + 1;
            }
            else {
                return middleIdx;
            }
        }
        if (target < middleValue) {
            rightIdx = middleIdx - 1;
        }
        else {
            leftIdx = middleIdx + 1;
        }
    }
    return -1;
}
exports.binarySearchLastIndex = binarySearchLastIndex;
function searchForRange(array, target, get) {
    get = get ? get : (element) => element;
    return [binarySearchFirstIndex(array, target, get), binarySearchLastIndex(array, target, get)];
}
exports.searchForRange = searchForRange;