917.Reverse Only Letters

Description

Given a string S, return the “reversed” string where all characters that are not a letter stay in the same place, and all letters reverse their positions.

题目链接：https://leetcode.com/problems/reverse-only-letters/

Difficulty: easy

Example 1:

Input: "ab-cd"
Output: "dc-ba"

Example 2:

Input: "a-bC-dEf-ghIj"
Output: "j-Ih-gfE-dCba"

Example 3:

Input: "Test1ng-Leet=code-Q!"
Output: "Qedo1ct-eeLg=ntse-T!"

Note:

S.length <= 100
33 <= S[i].ASCIIcode <= 122
S doesn’t contain \ or “

分析

updating

参考代码

class Solution(object):
def reverseOnlyLetters(self, S):
    letters = [c for c in S if c.isalpha()]
    ans = []
    for c in S:
        if c.isalpha():
            ans.append(letters.pop())
        else:
            ans.append(c)
    return "".join(ans)