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[pull] master from youngyangyang04:master #71

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Merged
pull merged 5 commits into AlgorithmAndLeetCode:master from youngyangyang04:master
Aug 29, 2022
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157 changes: 80 additions & 77 deletions problems/0347.前K个高频元素.md
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -268,99 +268,102 @@ func topKFrequent(nums []int, k int) []int {



javaScript:
JavaScript:
```js
/**
* @param {number[]} nums
* @param {number} k
* @return {number[]}
*/
var topKFrequent = function(nums, k) {
const map = new Map();

for(const num of nums) {
map.set(num, (map.get(num) || 0) + 1);
}
// js 没有堆 需要自己构造
class Heap {
constructor(compareFn) {
this.compareFn = compareFn;
this.queue = [];
}

// 添加
push(item) {
// 推入元素
this.queue.push(item);

// 创建小顶堆
const priorityQueue = new PriorityQueue((a, b) => a[1] - b[1]);
// 上浮
let index = this.size() - 1; // 记录推入元素下标
let parent = Math.floor((index - 1) / 2); // 记录父节点下标

// entry 是一个长度为2的数组,0位置存储key,1位置存储value
for (const entry of map.entries()) {
priorityQueue.push(entry);
if (priorityQueue.size() > k) {
priorityQueue.pop();
while (parent >= 0 && this.compare(parent, index) > 0) { // 注意compare参数顺序
[this.queue[index], this.queue[parent]] = [this.queue[parent], this.queue[index]];

// 更新下标
index = parent;
parent = Math.floor((index - 1) / 2);
}
}
}

const ret = [];
// 获取堆顶元素并移除
pop() {
// 堆顶元素
const out = this.queue[0];

for(let i = priorityQueue.size() - 1; i >= 0; i--) {
ret[i] = priorityQueue.pop()[0];
}
// 移除堆顶元素 填入最后一个元素
this.queue[0] = this.queue.pop();

return ret;
};
// 下沉
let index = 0; // 记录下沉元素下标
let left = 1; // left 是左子节点下标 left + 1 则是右子节点下标
let searchChild = this.compare(left, left + 1) > 0 ? left + 1 : left;

while (searchChild !== undefined && this.compare(index, searchChild) > 0) { // 注意compare参数顺序
[this.queue[index], this.queue[searchChild]] = [this.queue[searchChild], this.queue[index]];

function PriorityQueue(compareFn) {
this.compareFn = compareFn;
this.queue = [];
}
// 更新下标
index = searchChild;
left = 2 * index + 1;
searchChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
}

// 添加
PriorityQueue.prototype.push = function(item) {
this.queue.push(item);
let index = this.queue.length - 1;
let parent = Math.floor((index - 1) / 2);
// 上浮
while(parent >= 0 && this.compare(parent, index) > 0) {
// 交换
[this.queue[index], this.queue[parent]] = [this.queue[parent], this.queue[index]];
index = parent;
parent = Math.floor((index - 1) / 2);
}
}
return out;
}

// 获取堆顶元素并移除
PriorityQueue.prototype.pop = function() {
const ret = this.queue[0];

// 把最后一个节点移到堆顶
this.queue[0] = this.queue.pop();

let index = 0;
// 左子节点下标,left + 1 就是右子节点下标
let left = 1;
let selectedChild = this.compare(left, left + 1) > 0 ? left + 1 : left;

// 下沉
while(selectedChild !== undefined && this.compare(index, selectedChild) > 0) {
// 交换
[this.queue[index], this.queue[selectedChild]] = [this.queue[selectedChild], this.queue[index]];
index = selectedChild;
left = 2 * index + 1;
selectedChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
}
size() {
return this.queue.length;
}

return ret;
}
// 使用传入的 compareFn 比较两个位置的元素
compare(index1, index2) {
// 处理下标越界问题
if (this.queue[index1] === undefined) return 1;
if (this.queue[index2] === undefined) return -1;

return this.compareFn(this.queue[index1], this.queue[index2]);
}

PriorityQueue.prototype.size = function() {
return this.queue.length;
}

// 使用传入的 compareFn 比较两个位置的元素
PriorityQueue.prototype.compare = function(index1, index2) {
if (this.queue[index1] === undefined) {
return 1;
}
if (this.queue[index2] === undefined) {
return -1;
}
const topKFrequent = function (nums, k) {
const map = new Map();

return this.compareFn(this.queue[index1], this.queue[index2]);
}
for (const num of nums) {
map.set(num, (map.get(num) || 0) + 1);
}

// 创建小顶堆
const heap= new Heap((a, b) => a[1] - b[1]);

// entry 是一个长度为2的数组,0位置存储key,1位置存储value
for (const entry of map.entries()) {
heap.push(entry);

if (heap.size() > k) {
heap.pop();
}
}

// return heap.queue.map(e => e[0]);

const res = [];

for (let i = heap.size() - 1; i >= 0; i--) {
res[i] = heap.pop()[0];
}

return res;
};
```

TypeScript:
Expand Down
2 changes: 1 addition & 1 deletion problems/0541.反转字符串II.md
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@

[力扣题目链接](https://leetcode.cn/problems/reverse-string-ii/)

给定一个字符串 s 和一个整数 k,你需要对从字符串开头算起的每隔 2k 个字符的前 k 个字符进行反转。
给定一个字符串 s 和一个整数 k,从字符串开头算起, 每计数至 2k 个字符,就反转这 2k 个字符中的前 k 个字符。

如果剩余字符少于 k 个,则将剩余字符全部反转。

Expand Down

AltStyle によって変換されたページ (->オリジナル) /