给定一个数字列表和一个目标值，找出列表中和为目标值的两个数
def two_sum(list, target):
for i in range(len(list)):
a = target - list[i]
if a in list:
print([i, list.index(target - list[i])])
break
alist = [2, 7, 11, 15]
target = 9
two_sum(alist, target)
