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题目

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”]

我的想法

典型的双指针题～

class Solution {
       public char[] reverseString(char[] s) {
           if(s.length <= 0 || s == null) return null;        if(s.length == 1) return s;        int head = 0, tail = s.length - 1;        while(head <= tail){
               char temp = s[tail];            s[tail] = s[head];            s[head] = temp;            head++;            tail--;        }        return s;    }}

解答

这道题没啥好说的，如果现实中真的需要反转的话，直接用StringBuilder中的reverse()方法吧

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