【CodeForces 616D】Longest k-Good Segment

#include<cstdio>
#define ll long long
#define N 500005

int n,k;
int a[500005],num[1000005];
int l,r;
int s,ansl,ansr;

int main()
{
    scanf("%d%d",&n,&k);
    for(int i=1; i<=n; i++)
    {
        scanf("%d",&a[i]);
    }
    ansl=1;
    ansr=k;
    l=1;
    r=0;
    while(r<n)
    {
        r++;
        if(num[a[r]]==0)s++;
        num[a[r]]++;
        while(s>k)
        {
            num[a[l]]--;
            if(num[a[l]]==0)s--;
            l++;
        }
        if(r-l>ansr-ansl)
        {
            ansr=r;
            ansl=l;
        }
    }
    printf("%d %d",ansl,ansr);
    return 0;
}