排序，索引查找o_O

解题思路:

注意事项:

参考代码:

w = int(input())

n = int(input())

arr = []

for i in range(n):

    a = int(input())

    arr.append(a)

arr.sort()

left = 0

right = n - 1

m = 0

while left <= right:

    if arr[left] + arr[right] <= w:

        left += 1

    right -= 1

    m += 1

print(m)