Rust 力扣 - 2841. 几乎唯一子数组的最大和

题目描述

题解思路

我们遍历长度为k的窗口，用一个哈希表记录窗口内的所有元素（用来对窗口内元素去重），我们取哈希表中元素数量大于等于m的窗口总和的最大值

题解代码

use std::collections::HashMap;

impl Solution {
    pub fn max_sum(nums: Vec<i32>, m: i32, k: i32) -> i64 {
        let mut win = HashMap::new();

        let mut sum = 0;

        for i in 0..k as usize {
            win.insert(nums[i], i);
            sum += nums[i] as i64;
        }

        let mut ans = 0i64;

        if win.len() >= m as usize {
            ans = ans.max(sum);
        }

        for i in k as usize..nums.len() {
            if let Some(&start) = win.get(&nums[i-k as usize]) {
                if start == i - k as usize {
                    win.remove(&nums[i-k as usize]);
                }
            }

            win.insert(nums[i], i);

            sum += (nums[i] - nums[i-k as usize]) as i64;

            if win.len() >= m as usize {
                ans = ans.max(sum);
            }
        }

        ans
    }
}

题目链接

https://leetcode.cn/problems/maximum-sum-of-almost-unique-subarray/description/