leetcode.344 Reverse String

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

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

You may assume all the characters consist of

Example 1:

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

Example 2:

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

Solution

指標交換

class Solution:
    def reverseString(self, s: List[str]) -> None:
        """
        Do not return anything, modify s in-place instead.
        """
        n = len(s)
        l = 0
        r = n - 1
        while l<r:
            s[l],s[r] = s[r],s[l]
            l += 1
            r -= 1
 

異或交換

class Solution:
    def reverseString(self, s: List[str]) -> None:
        """
        Do not return anything, modify s in-place instead.
        """
        n = len(s)
        l = 0
        r = n - 1
        while l<r:
            s[l] = chr(ord(s[l]) ^ ord(s[r])) 
            s[r] = chr(ord(s[l]) ^ ord(s[r]))
            s[l] = chr(ord(s[l]) ^ ord(s[r]))
            l += 1
            r -= 1