SMMR-166: Subsegment Sum

#include <bits/stdc++.h>

using namespace std;

int n,S;
int row[100005];

int main(){
    scanf("%d%d",&n,&S);
    for(int i=1;i<=n;i++)
        scanf("%d",&row[i]);
    int l,r;
    l = r = 1;
    int sum = row[1];
    int ans = -1;
    while(r <= n){
        if(sum >= S){
            if(ans == -1)
                ans = r-l+1;
            else
                ans = min(ans,r-l+1);
            if(l!=r){
                sum -= row[l];
                l++;
            }
            else{
                r++;
                sum += row[r];
            }
        }
        else{
            r++;
            sum += row[r];
        }
    }
    printf("%d",ans);
}