class Solution {
    public String reverseWords(String s) {
        if(s==null || s.length()<=1) return s; 
        String[] sarr=s.split(" ");
        int len=sarr.length;
        StringBuilder sb=new StringBuilder(sarr[len-1]);
        for(int i=len-2;i>=0;i--){
            String temp=sarr[i];
            sb.append(" ").append(temp);
        }
        return sb.toString();
    }
}