题解 | #24点游戏算法#

# 递归过程就是穷举
# 不断地将list中穷举任意两个数的加减乘除，直到list中只剩下一个数
def fun(lst):
    n = len(lst)
    if n == 1:
        return abs(lst[0] - 24) < 1e-6
    for i in range(n):
        for j in range(n):          
            if j != i:
                nums = []
                for k in range(n):
                    if k!=i and k != j:
                        nums.append(lst[k])
                oprations = [lambda x,y:x+y, lambda x,y:x-y, lambda x,y:x*y]
                if abs(lst[j]) > 1e-6:
                    oprations.append(lambda x,y:x/y)
                for op in oprations:
                    nums.append(op(lst[i],lst[j]))
                    if fun(nums):
                        return True
                    nums.pop()
    return False

s = list(map(int, input().split()))
if fun(s):
    print('true')
else:
    print('false')