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feat: refactor top_k.ts (#899)

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This commit is contained in:
Justin Tse
2023-10-28 14:27:52 +08:00
committed by GitHub
parent f98b337144
commit c37f0981f0
2 changed files with 61 additions and 35 deletions
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46
codes/typescript/chapter_heap/my_heap.ts
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@ -122,32 +122,34 @@ class MaxHeap {
} }
/* Driver Code */ /* Driver Code */
/* 初始化大顶堆 */ if (require.main === module) {
const maxHeap = new MaxHeap([9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2]); /* 初始化大顶堆 */
console.log('\n输入列表并建堆后'); const maxHeap = new MaxHeap([9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2]);
maxHeap.print(); console.log('\n输入列表并建堆后');
maxHeap.print();
/* 获取堆顶元素 */ /* 获取堆顶元素 */
let peek = maxHeap.peek(); let peek = maxHeap.peek();
console.log(`\n堆顶元素为 ${peek}`); console.log(`\n堆顶元素为 ${peek}`);
/* 元素入堆 */ /* 元素入堆 */
const val = 7; const val = 7;
maxHeap.push(val); maxHeap.push(val);
console.log(`\n元素 ${val} 入堆后`); console.log(`\n元素 ${val} 入堆后`);
maxHeap.print(); maxHeap.print();
/* 堆顶元素出堆 */ /* 堆顶元素出堆 */
peek = maxHeap.pop(); peek = maxHeap.pop();
console.log(`\n堆顶元素 ${peek} 出堆后`); console.log(`\n堆顶元素 ${peek} 出堆后`);
maxHeap.print(); maxHeap.print();
/* 获取堆大小 */ /* 获取堆大小 */
const size = maxHeap.size(); const size = maxHeap.size();
console.log(`\n堆元素数量为 ${size}`); console.log(`\n堆元素数量为 ${size}`);
/* 判断堆是否为空 */ /* 判断堆是否为空 */
const isEmpty = maxHeap.isEmpty(); const isEmpty = maxHeap.isEmpty();
console.log(`\n堆是否为空 ${isEmpty}`); console.log(`\n堆是否为空 ${isEmpty}`);
}
export { MaxHeap }; export { MaxHeap };

50
codes/typescript/chapter_heap/top_k.ts
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@ -6,25 +6,49 @@
import { MaxHeap } from './my_heap'; import { MaxHeap } from './my_heap';
/* 元素入堆 */
function pushMinHeap(maxHeap: MaxHeap, val: number): void {
// 元素取反
maxHeap.push(-val);
}
/* 元素出堆 */
function popMinHeap(maxHeap: MaxHeap): number {
// 元素取反
return -maxHeap.pop();
}
/* 访问堆顶元素 */
function peekMinHeap(maxHeap: MaxHeap): number {
// 元素取反
return -maxHeap.peek();
}
/* 取出堆中元素 */
function getMinHeap(maxHeap: MaxHeap): number[] {
// 元素取反
return maxHeap.getMaxHeap().map((num: number) => -num);
}
/* 基于堆查找数组中最大的 k 个元素 */ /* 基于堆查找数组中最大的 k 个元素 */
function topKHeap(nums: number[], k: number): number[] { function topKHeap(nums: number[], k: number): number[] {
// 将堆中所有元素取反，从而用大顶堆来模拟小顶堆 // 初始化小顶堆
const invertedNums = nums.map((num) => -num); // 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 // 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 // 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++) { for (let i = k; i < nums.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 // 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 (invertedNums[i] < heap.peek()) { if (nums[i] > peekMinHeap(maxHeap)) {
heap.pop(); popMinHeap(maxHeap);
heap.push(invertedNums[i]); pushMinHeap(maxHeap, nums[i]);
} }
} }
// 取出堆中元素 // 返回堆中元素
const maxHeap = heap.getMaxHeap(); return getMinHeap(maxHeap);
// 对堆中元素取相反数
const invertedMaxHeap = maxHeap.map((num) => -num);
return invertedMaxHeap;
} }
/* Driver Code */ /* Driver Code */