【LeetCode】344. Reverse String

Difficulty:easy

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Description

https://leetcode.com/problems/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 printable ascii characters.

 

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"]

Intuition

use a pointer

 

Solution

    public void reverseString(char[] s) {
        for(int i=0; i<s.length/2; i++){
            char temp = s[i];
            s[i] = s[s.length-1-i];
            s[s.length-1-i]=temp;
        }
    }

　　

Complexity

Time complexity : O(n)

Space complexity : O(1)

 

 

 More:【目录】LeetCode Java实现