学步园

算出前缀和(就是前n项和...),加上t之后二分找结尾处,减出区间,穷举取最大.

二分,就是当你朴素地想的时候就是一项项加.

#include <cstdio>
using namespace std;
const int MAXN = 100005;
int sum[MAXN],n;
int max(int a, int b)
{
    int diff = b-a;
    return b - (diff & diff>>31 );
}
int bin(int x)
{
    int l = 0,r = n-1, mid, ans = 0;
    while(l<=r)
    {
        mid = (l+r)>>1;
        if(sum[mid]==x) return mid;
        if(sum[mid]>x)  r = mid - 1;
        else
        {
            ans = mid;
            l = mid + 1;
        }
    }
    return ans;
}
int main()
{
    int t,ans = 0;
    int a[MAXN];
    scanf("%d %d",&n,&t);
    for(int i=0;i<n;i++)
    {
        scanf("%d",a+i);
        if(i)   sum[i] = sum[i-1]+a[i];
        else    sum[0] = a[0];
    }
    for(int i=0;i<n;i++)
    {
        if(a[i]<=t)
        {
            int tmp = bin(sum[i-1]+t);
            ans = max(ans,tmp-i+1);
        }
    }
    printf("%d\n",ans);
}