Score : 600 points
You are given an integer sequence of length N, a = {a_1, a_2, …, a_N}, and an integer K.
a has N(N+1)/2 non-empty contiguous subsequences, {a_l, a_{l+1}, …, a_r} (1 ≤ l ≤ r ≤ N). Among them, how many have an arithmetic mean that is greater than or equal to K?
Input is given from Standard Input in the following format:
N K a_1 a_2 : a_N
Print the number of the non-empty contiguous subsequences with an arithmetic mean that is greater than or equal to K.
3 6 7 5 7
5
All the non-empty contiguous subsequences of a are listed below:
Their means are 7, 6, 19/3, 5, 6 and 7, respectively, and five among them are 6 or greater. Note that {a_1} and {a_3} are indistinguishable by the values of their elements, but we count them individually.
1 2 1
0
7 26 10 20 30 40 30 20 10
13