백준 3273 - 두 수의 합 (파이썬)

Answer

n = int(input())
a = sorted(list(map(int, input().split())))
x = int(input())

left = 0
right = n - 1
answer = 0

while left < right:
    tmp = a[left] + a[right]

    if tmp == x:
        answer += 1
        right -= 1
    elif tmp > x:
        right -= 1
    else:
        left += 1

print(answer)