107w-heap/index.js

提供js堆排序(优先级队列)数据结构

// 更高性能（其实不明所以）去掉！就是最大堆
/*
传入回调函数morethen，定义比较方法，> 最小堆， < 最大堆
最小堆
new BigHeap(function (i, j) {
  return this.heap[i] > this.heap[j];
}) 
最大堆
new BigHeap(function (i, j) {
  return this.heap[i] < this.heap[j];
}) 
*/
class BigHeap {
  constructor(morethan = function(i, j) {return this.heap[i] > this.heap[j]}) {
    this.morethan = morethan
    this.heap = [];
    this.heap[0] = null; // 占位，不使用
    this.count = 0; // 堆元素个数
  }
  insert(n) {
    this.heap.push(n);
    this.count++;
    this.swim(this.heap.length - 1);
  }
  swim(i) {
    while (i > 1 && !this.morethan(i, this.parent(i))) {
      this.each(i, this.parent(i));
      i = this.parent(i);
    }
  }
  sink(i) {
    while (i < this.heap.length) {
      let left = 2 * i,
        right = 2 * i + 1,
        temp = i,
        len = this.heap.length;
      if (left < len && !this.morethan(left, temp)) temp = left;
      if (right < len && !this.morethan(right, temp)) temp = right;
      if (temp == i) return;
      this.each(temp, i);
      i = temp;
    }
  }
  parent(i) {
    return i >> 1;
  }
  each(i, j) {
    [this.heap[i], this.heap[j]] = [this.heap[j], this.heap[i]];
  }
  delMax() {
    this.each(1, this.heap.length - 1);
    this.count--;
    let max = this.heap.pop();
    this.sink(1);
    return max;
  }
}
module.exports = BigHeap