洛谷P1638 逛画展(贪心)

P1638 逛画展

题解：维护一个涵盖所有画师的滑动窗口，尽量让窗口内每种画的数量保持在$1$，记录长度最短的窗口端点。

代码

#include<bits/stdc++.h>

using namespace std;
int n,m,d[1000010],now[2001];

int main()
{
#ifndef ONLINE_JUDGE
    freopen("input.in","r",stdin);
#endif
    cin>>n>>m;
    for(int i = 1; i <= n; ++i){
        cin>>d[i];
    }

    int front = 1, rear = 1, ans_X = 1, ans_Y = 1e7, cnt = 0;
    while(front <= rear){
        if(now[d[rear]] == 0) cnt++;
        if(rear<=n)
        now[d[rear++]]++;
        for( ; now[d[front]] > 1; front++)
            now[d[front]]--;
        if(cnt >= m){
            if(rear - front < ans_Y - ans_X)
                ans_X = front, ans_Y = rear;
        }
        if(rear == n + 1) break;
    }
    cout<<ans_X<<' '<<ans_Y-1<<endl;
    return 0;
}