python编程---example14

寻找列表中满足两数之和等于目标值的元素的下标。

def sum_of_two(arr,target):dic = {}for i,x in enumerate(arr):j = dic.get(target-x,-1)if j != -1:return((j,i))else:dic[x] = ireturn([])arr = [2,7,4,9]
target = 6
print(sum_of_two(arr,target))