ReverseString2 [source code]

public class ReverseString2 {
    public String reverseString(String s) {
        char[] words = s.toCharArray();
        int i = 0;
        int j = words.length - 1;
        while ( i<j ) {
            char tmp = words[j];
            words[j] = words[i];
            words[i] = tmp;
            i++;
            j--;
        }
        return new String(words);
    }
}

这个版本就直接接受不超时了,不知道什么原理. 不过 string 和char array之间的转换还是要学会; 时间是3ms, 55%, 凑合差不多了, 可以不折腾了.

Problem Description

Write a function that takes a string as input and returns the string reversed.

Example:
Given s = "hello", return "olleh".