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

Example:

public String reverseString(String s) {        char[] ss = s.toCharArray();        int j = ss.length - 1, i = 0;        char temp;        while (i < j) {            temp = ss[i];            ss[i] = ss[j];            ss[j] = temp;            i++;            j--;        }        return String.valueOf(ss);    }

AC了，我想着用栈会不会更加快，没想到。。。

//超时了    public String reverseString(String s) {        Stack
     
       stack = new Stack
      
       ();        String str = "";        for (int i = 0; i < s.length(); i++)            stack.add(s.charAt(i));        while(!stack.isEmpty())            str += stack.pop();        return str;    }
      
     

这个不能AC