题解

地铁上瞎想出来的

#include <iostream>
#include <cstdio>
using namespace std;
int a[100005];
signed main(){
	int n;
    long long m;
	scanf("%d%lld", &n, &m);
	for(int i = 1; i <= n; i++){
		scanf("%d", &a[i]);
	}
    long long mx = 0, ct = 0, st = 1;
	for(int i = 1; i <= n; i++){
		ct += a[i];//采了
        while(ct > m){
            ct -= a[st++];//超出最大值，前面几个的就不采
        }
        mx = max(mx, ct);//更新最大值
	}
    printf("%lld", mx);
	

	return 0;
}

时间复杂度：$O(n)$