hello-algo/codes/rust/chapter_heap/top_k.rs
rongyi 7b1094318b
cargo fmt rust code (#1131)
* cargo fmt code

* Add empty line to seperate unrelated comments

* Fix review

* Update bubble_sort.rs

* Update merge_sort.rs

---------

Co-authored-by: Yudong Jin <krahets@163.com>
2024-03-16 02:13:41 +08:00

39 lines
1.1 KiB
Rust

/*
* File: top_k.rs
* Created Time: 2023-07-16
* Author: night-cruise (2586447362@qq.com)
*/
include!("../include/include.rs");
use std::cmp::Reverse;
use std::collections::BinaryHeap;
/* 基于堆查找数组中最大的 k 个元素 */
fn top_k_heap(nums: Vec<i32>, k: usize) -> BinaryHeap<Reverse<i32>> {
// BinaryHeap 是大顶堆,使用 Reverse 将元素取反,从而实现小顶堆
let mut heap = BinaryHeap::<Reverse<i32>>::new();
// 将数组的前 k 个元素入堆
for &num in nums.iter().take(k) {
heap.push(Reverse(num));
}
// 从第 k+1 个元素开始,保持堆的长度为 k
for &num in nums.iter().skip(k) {
// 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 num > heap.peek().unwrap().0 {
heap.pop();
heap.push(Reverse(num));
}
}
heap
}
/* Driver Code */
fn main() {
let nums = vec![1, 7, 6, 3, 2];
let k = 3;
let res = top_k_heap(nums, k);
println!("最大的 {} 个元素为", k);
print_util::print_heap(res.into_iter().map(|item| item.0).collect());
}