class Solution {
    public String reverseWords(String s) {

        String[] strs = s.split(" ");

        StringBuffer sb = new StringBuffer();
        for(int i = 0 ; i < strs.length ; i++){
            char[] chars = strs[i].toCharArray();
            int begin = 0;
            int end = chars.length-1;
            while(begin <= end){
                swap(chars,begin++,end--);
            }
            sb.append(chars);
            if(i != strs.length - 1){
                sb.append(" ");
            }
        }

        return sb.toString();
    }

    public void swap(char[] chars,int begin,int end){
        char temp = chars[begin];
        chars[begin] = chars[end];
        chars[end] = temp;
    }
}