SMMR-166: Subsegment Sum

#include <bits/stdc++.h>

using namespace std;
int ar[100010];

const int INF = 2e9;

int main(){

    int n, s;
    scanf("%d%d", &n, &s);

    int start = 1, ending = 0, ans = INF, sum = 0;
    for(int i=1;i<=n;i++){
        scanf("%d", &ar[i]);
        sum += ar[i];
        while(sum >= s){
            ans = min(ans, i - start + 1);
            if(sum - ar[start] >= s) sum -= ar[start];
            else break;
            start ++;
        }
    }

    if(ans == INF) printf("-1");
    else printf("%d", ans);

    return 0;
}