Subsegmentsum

#include<stdio.h>
typedef long long int ll;

int main()
{
    int n;
    ll s;
    scanf("%d %lld",&n,&s);
    ll arr[n+1];
    ll qs[n+1];
    qs[0] = 0;
    for(int i = 1 ; i <= n ; i ++){
        scanf("%lld",&arr[i]);
        qs[i] = qs[i-1] + arr[i];
    }
    int mina = n+1;
    int L = 1 , R = n; //bsearch on size
    while(L <= R){
        int M = (L+R)/2;
        bool check = false;
        for(int l = 1 ; l <= n && !check ; l ++){
            int r = l + M - 1;
            if(r > n)break;
            ll sum = qs[r] - qs[l-1];
            if(sum >= s){
                check = true;
                break;
            }
        }
        if(check){
            if(M < mina)mina = M;
            R = M - 1;
        }else{
            L = M + 1;
        }
    }
    printf("%d",(mina == n + 1 ? -1 : mina));
    return 0;
}