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