public class Solution {
    public String reverseString(String s) {
        if(s.length()==0) return s;
        int start=0,end=s.length()-1;
        char[] c=s.toCharArray();
        while(start<end){
            char temp=c[start];
            c[start]=c[end];
            c[end]=temp;
            start++;
            end--;
        }
        String ss=new String(c);
        return ss;
    }
}