前端堆的相关算法

javascript实现最小堆数据结构

class MinHeap {
  constructor() {
    this.heap = []
  }
  //查找父级元素
  getParentIndex(index) {
    return (index - 1) >> 1
  }
  //查找左节点
  getLeftIndex(index) {
    return index * 2 + 1
  }
  getRightIndex(index) {
    return index * 2 + 2
  }
  swap(i1, i2) {
    [this.heap[i1], this.heap[i2]] = [this.heap[i2], this.heap[i1]]
  }
  //插入元素上浮
  shiftUp(index) {
    if (index === 0) {
      return
    }
    const parentIndex = this.getParentIndex(index)
    if (this.heap[index] < this.heap[parentIndex]) {
      this.swap(index, parentIndex)
      this.shiftUp(parentIndex)
    }
  }
  //删除堆尾元素后下沉
  shiftDown(index) {
    const leftIndex = this.getLeftIndex(index)
    const rightIndex = this.getRightIndex(index)
    if (this.heap[leftIndex] < this.heap[index]) {
      this.swap(leftIndex, index)
      this.shiftDown(leftIndex)
    }
    if (this.heap[rightIndex] < this.heap[index]) {
      this.swap(rightIndex, index)
      this.shiftDown(rightIndex)
    }
  }
  //logK
  insert(value) {
    this.heap.push(value)
    this.shiftUp(this.heap.length - 1)
  }
  pop() {
    this.heap[0] = this.heap.pop()
    this.shiftDown(0)
  }
  peek() {
    return this.heap[0]
  }
  size() {
    return this.heap.length
  }
}
let h = new MinHeap()