This code belongs to java and also this code is beginner friendly,

static String reverseStringWordWise(String input) {

        // Write your code here

        String ans = "";

        int i = input.length()-1;

        while(i>=0){

            while(i>=0&&input.charAt(i)==' ')i--;

            int j = i;

            while(i>=0&&input.charAt(i)!=' ')i--;

            if(ans.isEmpty()){

                ans = ans.concat(input.substring(i+1,j+1));

            }else{

                 ans = ans.concat(" "+input.substring(i+1,j+1));

            }

        }

        return ans;

    }