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703-KthLargestElementinaStream.js
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703-KthLargestElementinaStream.js
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/**
* @param {number} k
* @param {number[]} nums
*/
var KthLargest = function(k, nums) {
//排序后,小顶堆; 先变成堆形态
this.heap = new Heap();
this.k = k;
for (var i = 0; i < nums.length; i++) {
if (this.heap.length < k) {
this.heap.push(nums[i]);
} else if (this.heap.peek() < nums[i]) {
this.heap.pop();
this.heap.push(nums[i]);
}
}
};
/**
* @param {number} val
* @return {number}
*/
KthLargest.prototype.add = function(val) {
if (this.heap.length < this.k) {
this.heap.push(val);
} else if (this.heap.peek() < val) {
this.heap.pop();
this.heap.push(val);
}
return this.heap.peek();
};
/**
* Your KthLargest object will be instantiated and called as such:
* var obj = new KthLargest(k, nums)
* var param_1 = obj.add(val)
*/
class Heap extends Array {
//继承自Array
//创建一个数量为k的小根堆
constructor(compare = (a, b) => a - b, initialValues) {
super();
this.compare = compare;
}
swap(i, j) {
var t = this[i];
this[i] = this[j];
this[j] = t;
} //转换过程1
heapUp(idx) {
var pIdx = (idx - 1) >> 1;
if (idx > 0 && this.compare(this[idx], this[pIdx]) < 0) {
this.swap(idx, pIdx);
this.heapUp(pIdx);
}
}
heapDown(idx) {
if (idx < this.length) {
var max = idx;
var l = idx * 2 + 1;
var r = l + 1;
if (l < this.length && this.compare(this[l], this[max]) < 0) {
max = l;
}
if (r < this.length && this.compare(this[r], this[max]) < 0) {
max = r;
}
if (idx !== max) {
this.swap(idx, max);
this.heapDown(max);
}
}
} //转换过程
//转换二叉堆
peek() {
return this[0];
}
push(val) {
super.push(val);
this.heapUp(this.length - 1);
}
pop() {
var result = this[0];
var last = super.pop();
if (this.length > 0) {
this[0] = last;
this.heapDown(0);
}
return result;
}
}
// 第二种方法
/**
* @param {number} k
* @param {number[]} nums
*/
var KthLargest = function(k, nums) {
this.k = k;
this.arr = [];
for (var i = 0; i < nums.length; i++) {
this.add(nums[i]);
}
};
/**
* @param {number} val
* @return {number}
*/
KthLargest.prototype.add = function(val) {
var sign = true;
if (!this.arr.length) {
this.arr.push(val);
} else {
var i = 0;
while (i < this.arr.length) {
if (val < this.arr[i]) {
this.arr.splice(i, 0, val);
sign = false;
break;
}
i++;
}
if (sign) {
this.arr.push(val);
}
if (this.arr.length > this.k) {
this.arr.shift();
}
}
return this.arr[0];
};
/**
* Your KthLargest object will be instantiated and called as such:
* var obj = new KthLargest(k, nums)
* var param_1 = obj.add(val)
*/