POJ 3061 Subsequence 尺取法，一个屌屌的O(n)算法

#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <typeinfo>
#include <fstream>
typedef long long ll;
using namespace std;
//freopen("D.in","r",stdin);
//freopen("D.out","w",stdout);
#define sspeed ios_base::sync_with_stdio(0);cin.tie(0)
#define maxn 100001
const int inf=0x7fffffff;   //无限大
int a[maxn];
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int n,s;
        cin>>n>>s;
        for(int i=0;i<n;i++)
        {
            cin>>a[i];
        }
        ll sum=a[0];
        int st=0,en=0;
        int minn=inf;
        while(en!=n&&st<=en)
        {
            //cout<<st<<" "<<en<<" "<<sum<<endl;
            if(sum>=s)
            {
                minn=min(minn,en-st+1);
                sum-=a[st];
                st++;
            }
            if(sum<s)
            {
                en++;
                sum+=a[en];
            }
        }
        if(minn==inf)
            cout<<"0"<<endl;
        else
            cout<<minn<<endl;
    }
    return 0;
}