Submission #6319302

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Source Code Expand

import sys
input = sys.stdin.readline
from itertools import accumulate

N,K = map(int,input().split())
A = [int(input()) - K for _ in range(N)]
Acum = [0] + list(accumulate(A))

a_to_i = {a:i for i,a in enumerate(sorted(set(Acum)), 1)}

B = [a_to_i[a] for a in Acum]

L = len(a_to_i) + 1
tree = [0] * (L+1)

# 過去に自分以下の値が何回出てきているのか
def BIT_update(tree, x):
    while x <= L:
        tree[x] += 1
        x += x & (-x)

def BIT_sum(tree, x):
    s = 0
    while x:
        s += tree[x]
        x -= x & (-x)
    return s

answer = 0
for b in B:
    answer += BIT_sum(tree,b)
    BIT_update(tree,b)

print(answer)

Submission Info

Judge Result