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feat: add top_k.c and refactor top_k.js (#889)

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* Add top_k.c based on my_heap.c

* Improve the implementation of top_k.js

* Add a comment to top_k
This commit is contained in:
Yudong Jin
2023-10-26 02:54:19 +08:00
committed by GitHub
parent 9f4076d1c1
commit 7822bf9cd4
13 changed files with 190 additions and 73 deletions
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46
codes/javascript/chapter_heap/my_heap.js
View File

@ -123,33 +123,35 @@ class MaxHeap {
}
/* Driver Code */
/* 初始化大顶堆 */
const maxHeap = new MaxHeap([9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2]);
console.log('\n输入列表并建堆后');
maxHeap.print();
if (require.main === module) {
/* 初始化大顶堆 */
const maxHeap = new MaxHeap([9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2]);
console.log('\n输入列表并建堆后');
maxHeap.print();
/* 获取堆顶元素 */
let peek = maxHeap.peek();
console.log(`\n堆顶元素为 ${peek}`);
/* 获取堆顶元素 */
let peek = maxHeap.peek();
console.log(`\n堆顶元素为 ${peek}`);
/* 元素入堆 */
let val = 7;
maxHeap.push(val);
console.log(`\n元素 ${val} 入堆后`);
maxHeap.print();
/* 元素入堆 */
let val = 7;
maxHeap.push(val);
console.log(`\n元素 ${val} 入堆后`);
maxHeap.print();
/* 堆顶元素出堆 */
peek = maxHeap.pop();
console.log(`\n堆顶元素 ${peek} 出堆后`);
maxHeap.print();
/* 堆顶元素出堆 */
peek = maxHeap.pop();
console.log(`\n堆顶元素 ${peek} 出堆后`);
maxHeap.print();
/* 获取堆大小 */
let size = maxHeap.size();
console.log(`\n堆元素数量为 ${size}`);
/* 获取堆大小 */
let size = maxHeap.size();
console.log(`\n堆元素数量为 ${size}`);
/* 判断堆是否为空 */
let isEmpty = maxHeap.isEmpty();
console.log(`\n堆是否为空 ${isEmpty}`);
/* 判断堆是否为空 */
let isEmpty = maxHeap.isEmpty();
console.log(`\n堆是否为空 ${isEmpty}`);
}
module.exports = {
MaxHeap,

50
codes/javascript/chapter_heap/top_k.js
View File

@ -6,25 +6,49 @@
const { MaxHeap } = require('./my_heap');
/* 元素入堆 */
function pushMinHeap(maxHeap, val) {
// 元素取反
maxHeap.push(-val);
}
/* 元素出堆 */
function popMinHeap(maxHeap) {
// 元素取反
return -maxHeap.pop();
}
/* 访问堆顶元素 */
function peekMinHeap(maxHeap) {
// 元素取反
return -maxHeap.peek();
}
/* 取出堆中元素 */
function getMinHeap(maxHeap) {
// 元素取反
return maxHeap.getMaxHeap().map((num) => -num);
}
/* 基于堆查找数组中最大的 k 个元素 */
function topKHeap(nums, k) {
// 使用大顶堆 MaxHeap ，对数组 nums 取相反数
const invertedNums = nums.map((num) => -num);
// 初始化小顶堆
// 请注意：我们将堆中所有元素取反，从而用大顶堆来模拟小顶堆
const maxHeap = new MaxHeap([]);
// 将数组的前 k 个元素入堆
const heap = new MaxHeap(invertedNums.slice(0, k));
for (let i = 0; i < k; i++) {
pushMinHeap(maxHeap, nums[i]);
}
// 从第 k+1 个元素开始，保持堆的长度为 k
for (let i = k; i < invertedNums.length; i++) {
// 若当前元素小于堆顶元素，则将堆顶元素出堆、当前元素入堆
if (invertedNums[i] < heap.peek()) {
heap.pop();
heap.push(invertedNums[i]);
for (let i = k; i < nums.length; i++) {
// 若当前元素大于堆顶元素，则将堆顶元素出堆、当前元素入堆
if (nums[i] > peekMinHeap(maxHeap)) {
popMinHeap(maxHeap);
pushMinHeap(maxHeap, nums[i]);
}
}
// 取出堆中元素
const maxHeap = heap.getMaxHeap();
// 对堆中元素取相反数
const invertedMaxHeap = maxHeap.map((num) => -num);
return invertedMaxHeap;
// 返回堆中元素
return getMinHeap(maxHeap);
}
/* Driver Code */