luogu_P1638 visiting the exhibition

Scale borrowing, move the right point to the right, it will not move to the left point, then move the right point, always, always been like this

#include<iostream> 
#include<cstdio>

#define ri register int
#define u int

namespace opt {
    
    inline u in() {
        u x(0),f(1);
        char s(getchar());
        while(s<'0'||s>'9') {
            if(s=='-') f=-1;
            s=getchar();
        }
        while(s>='0'&&s<='9') {
            x=(x<<1)+(x<<3)+s-'0';
            s=getchar();
        }
        return x*f;
    }
    
}

using opt::in;

#define NN 1000005

namespace mainstay {
    
    u N,M,cnt,ans[3]={0x7fffffff},vt[NN],a[NN];
    
    inline void solve(){
        N=in(),M=in();
        for(ri i(1);i<=N;++i) a[i]=in();
        u l(1),r(0);
        while(1){
            if(l>=N||r>=N) break;
            if(!vt[a[r+1]]) ++cnt;
            ++vt[a[++r]];
            while(cnt==M){
                if(r-l+1<ans[0]){
                    ans[0]=r-l+1,ans[1]=l,ans[2]=r;
                }
                --vt[a[l++]];
                if(!vt[a[l-1]]) --cnt;
            }
        }
        std::cout<<ans[1]<<" "<<ans[2];
    }
    
}

int main() {
    
    //freopen("x.txt","r",stdin);
    std::ios::sync_with_stdio(false);
    mainstay::solve();
    
}