python - 编写一个合并两个列表的函数，交替两个列表中的元素。Python代码

Question

例如如果 a = [1, 4, 9, 16] 和 b = [9, 7, 4, 9, 11]，函数返回一个新列表，result = [1, 9, 4, 7, 9, 4 , 16, 9, 11]

这是我到目前为止的代码。

def merge(a,b):
    mergedList =[]
    for i in range(len(a)):
        mergedList.append(a[i])
        mergedList.append(b[i])

def main():
    a = [1,4,9,16]
    b = [9,7,4,9,11]
    print("List a is", a)
    print("List b is", b)
    result = merge(a,b)
    print("The merged list is", result)
main()

我得到的输出是

List a is [1,4,9,16]
List b is [9,7,4,9,11]
The merged list is None

有谁知道为什么新合并列表的输出为无？

Answer 1

您尚未返回合并列表。因此它的值为无。将第一个函数更改为：

def merge(a,b):
    mergedList =[]
    for i in range(len(a)):
        mergedList.append(a[i])
        mergedList.append(b[i])
    return mergedlist