String - 344. Reverse String

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 printable ascii characters.

Example 1:

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

思路：

two pointers

代码：

java：

class Solution {

    public void reverseString(char[] s) {
        if (s == null || s.length == 0) return;
        
        int i = 0, j = s.length - 1;
        while(i < j) {
            char temp = s[i];
            s[i++] = s[j];
            s[j--] = temp;
        }
    }
}