CodeForces 616D Longest k-Good Segment

用队列维护一下即可

#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
using namespace std;

const int maxn=500000+10;
int n,k;
int a[maxn];
int tot[1000000+10];
struct Node
{
    int id;
    int val;
} node[maxn];
queue<Node>Q;

int main()
{
    scanf("%d%d",&n,&k);
    for(int i=1; i<=n; i++)
    {
        scanf("%d",&a[i]);
        node[i].id=i;
        node[i].val=a[i];
    }

    memset(tot,0,sizeof tot);
    int ans=0,ansl,ansr;
    int now=0;

    for(int i=1; i<=n; i++)
    {
        Q.push(node[i]);
        if(tot[node[i].val]==0) now++;
        tot[node[i].val]++;
        if(now<=k)
        {
            Node head=Q.front();
            if(node[i].id-head.id+1>ans)
            {
                ans=node[i].id-head.id+1;
                ansl=head.id;
                ansr=node[i].id;
            }
        }
        else if(now>k)
        {
            while(1)
            {
                Node head=Q.front();
                if(tot[head.val]==1) now--;
                tot[head.val]--;
                Q.pop();
                if(now==k) break;
            }

            Node head=Q.front();
            if(node[i].id-head.id+1>ans)
            {
                ans=node[i].id-head.id+1;
                ansl=head.id;
                ansr=node[i].id;
            }
        }
    }
    printf("%d %d
",ansl,ansr);
    return 0;
}