#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, it...