题解 | #24点游戏算法#

#递归
import sys

def helper(arr, item):

    if item < 1:
        return False
    if len(arr) == 1:
        return arr[0] == item
    for i in range(len(arr)):
        L = arr[:i] + arr[i+1:]
        v = arr[i]
        if helper(L, item-v) or helper(L, item+v) or helper(L, item*v) or helper(L, item/v):
            return True
    return False

while True:
    try:
        arr = list(map(int, input().split()))
        if helper(arr, 24):
            print("true")
        else:
            print("false")
    except:
        break