344. Reverse String

Problem

Write a function that reverses a string. The input string is given as an array of characters s.

You must do this by modifying the input array in-place with O(1) extra money.

Example 1:

Input : s = ["h","e","l","l","o"]
Output : ["o","l","l","e","h"]

Example 2:

Input : s = ["H","a","n","n","a","h"]
Output : ["h","a","n","n","a","H"]

Constraints

• 1 <= s.length <= 10^5
• s[i] is a printable ascii character.

코드

1. 내장 함수

class Solution(object):
    def reverseString(self, s):
        """
        :type s: List[str]
        :rtype: None Do not return anything, modify s in-place instead.
        """
        s.reverse()

2. two pointer

class Solution(object):
    def reverseString(self, s):
        """
        :type s: List[str]
        :rtype: None Do not return anything, modify s in-place instead.
        """
        left, right = 0, len(s)-1
        while left < right :
            s[left],s[right]=s[right],s[left]
            left, right = left + 1, right - 1