确实大差不差

二分解法：

#include<stdio.h>

long long a[200010];
long long h[200010];

int main()
{
	int n;
	long long mi, mx, ans = 0;
	scanf("%d %lld %lld", &n, &mi, &mx);
	for(int i = 1; i <= n; i++)
	{
		scanf("%lld", &a[i]);
		h[i] = h[i - 1] + a[i];//前缀和计算
	}
	for(int i = 1; i <= n; i++)
	{
		int l1 = i, r1 = n;
		if(h[r1] - h[i - 1] >= mi)
		{
			while(l1 < r1)//二分查大于等于最小边界值有多少个区间
			{
				int miid = (l1 + r1) / 2;
				if(h[miid] - h[i - 1] >= mi)
					r1 = miid;
				else
					l1 = miid + 1;
			}
			ans += n - l1 + 1;//ans加上这些区间个数
			l1 = i, r1 = n;
			if(h[r1] - h[i - 1] > mx)
			{
				while(l1 < r1)//二分查大于最大边界值有多少个区间
				{
					int miid = (l1 + r1) / 2;
					if(h[miid] - h[i - 1] > mx)
						r1 = miid;
					else
						l1 = miid + 1;
				}
				ans -= n - l1 + 1;//ans减去这些超出最大值的区间个数
			}
		}
	}
	printf("%lld", ans);
	return 0;
}