Author: lllyouo
Date: 20251016
tag: 前缀和、队列
link: https://www.luogu.com.cn/problem/P3662

问题描述

link

分析

略

参考代码

队列

#include <bits/stdc++.h>
using namespace std;

int n, k, b, a[100010];

int main() {
    cin >> n >> k >> b;
    for (int i = 1; i <= b; i++) {
        int x; cin >> x;
        a[x] = 1;
    }

    queue<int> q;
    int ans = 0;
    for (int i = 1; i <= k; i++) {
        q.push(i);
        if (a[i]) ans++;
    }

    int cnt = ans;
    for (int i = k + 1; i <= n; i++) {
        q.push(i);
        if (a[i]) cnt++;
        if (a[q.front()]) cnt--;
        q.pop();
        ans = min(ans, cnt);
    }
    cout << ans << endl;

    return 0;
}

前缀和

#include <bits/stdc++.h>
using namespace std;

int n, k, b, s[100010];

int main() {
    cin >> n >> k >> b;
    for (int i = 1; i <= b; i++) {
        int x; cin >> x;
        s[x] = 1;
    }
    for (int i = 1; i <= n; i++) s[i] += s[i - 1];

    int ans = 1e9;
    for (int i = k; i <= n; i++) {
        ans = min(ans, s[i] - s[i - k]);
    }
    cout << ans << endl;

    return 0;
}