bisect_right, bisect_left

배열에서 특정한 값의 갯수 구하기

from bisect import bisect_left, bisect_right

def count_by_range(a, left_value, right_value):
	right_index = bisect_right(a, right_value)
	left_index = bisect_left(a, left_value)
	return right_index - left_index

a = [1, 2, 3, 3, 3, 3, 4, 4, 8, 8, 9]

print(count_by_range(a, 4, 4))

print(count_by_range(a, -1, 3))