1187: 子序列问题III

二分查找+前缀和

#include <bits/stdc++.h>
using namespace std;
const int N=1e5+10;
typedef long long LL;
LL pred[N];
int a[N],n,S;
bool judge(int mid){
	for(int i=mid;i<=n;i++){
		if(pred[i]-pred[i-mid]>=S)
			return true;
	}
	return false;
}
int main(){
	while(scanf("%d%d",&n,&S)!=EOF){
//		memset(pred,0,sizeof(pred));
//		memset(a,0,sizeof(a));
		for(int i=1;i<=n;i++){
			scanf("%d",&a[i]);
			pred[i]=pred[i-1]+a[i];
		}
		if (pred[n]<S) 
			{cout<<0<<endl;
			 continue;
			}
		int l=1,r=n,mid;
		while(l<r){
			mid = l + (r-l)/2;
			if(judge(mid)) r=mid;
			else l = mid+1;
		}
		
		printf("%d\n",l);
	}
	return 0;
}