堆排序的刪除和添加

function Heap(type = 'min') {
  this.type = type;
  this.value = [];
}

Heap.prototype.create = function () {
  const length = this.value.length;
  // 構建大頂堆 
  for (let i = Math.floor((length / 2) - 1); i >= 0; i--) {
    this.ajust(i, length);
  }
}

Heap.prototype.ajust = function (index, length) {
  const array = this.value;
  for (let i = 2 * index + 1; i < length; i = 2 * i + 1) {
    if (i + 1 < length) {
      if ((this.type === 'max' && array[i + 1] > array[i]) || // 找出2個孩子最大的一個
        (this.type === 'min' && array[i + 1] < array[i])) {
        i++; 
      }
    }
    if ((this.type === 'max' && array[index] < [array[i]]) || // 父節點小於孩子節點就替換
      (this.type === 'min' && array[index] > [array[i]])) {
      [array[index], array[i]] = [array[i], array[index]];
      index = i;
    } else {
      break;
    }
  }
}
// 由於堆屬於優先隊列 只能從末尾添加
Heap.prototype.add = function (element) {
  const array = this.value;
  array.push(element);
  if (array.length > 1) {
    let index = array.length - 1;
    let target = Math.floor((index - 1) / 2);
    while (target >= 0) {
      if ((this.type === 'min' && array[index] < array[target]) ||
        (this.type === 'max' && array[index] > array[target])) {
        [array[index], array[target]] = [array[target], array[index]]
        index = target;
        target = Math.floor((index - 1) / 2);
      } else {
        break;
      }
    }
  }
}

Heap.prototype.pop = function () {
  const array = this.value;
  let result = null;
  if (array.length > 1) {
    result = array[0];
    array[0] = array.pop();
    this.ajust(0, array.length);
  } else if (array.length === 1) {
    return array.pop();
  }
  return result;
}

var heap = new Heap('max');
heap.add(6)
heap.add(10)
heap.add(12)

console.log(heap.value);
console.log(heap.pop());
console.log(heap.value)