package string;

import java.util.ArrayList;

import java.util.List;

import java.util.StringTokenizer;

/**

* Created by gouthamvidyapradhan on 04/07/2017.

* Given an input string, reverse the string word by word.

For example,

Given s = "the sky is blue",

return "blue is sky the".

Clarification:

What constitutes a word?

A sequence of non-space characters constitutes a word.

Could the input string contain leading or trailing spaces?

Yes. However, your reversed string should not contain leading or trailing spaces.

How about multiple spaces between two words?

Reduce them to a single space in the reversed string.

*/

public class ReverseWordsInAString {

public static void main(String[] args) throws Exception{

System.out.println(new ReverseWordsInAString().reverseWords(" the sky is blue"));

}

public String reverseWords(String s) {

if(s == null || s.isEmpty()) return "";

StringBuilder sb = new StringBuilder(s.trim());

String reverse = sb.reverse().toString();

StringTokenizer st = new StringTokenizer(reverse, " ");

List<String> list = new ArrayList<>();

while(st.hasMoreTokens()){

list.add(st.nextToken());

}

for(int i = 0, l = list.size(); i < l; i ++){

String str = list.get(i);

String newStr = new StringBuilder(str).reverse().toString();

list.set(i, newStr);

}

StringBuilder result = new StringBuilder();

for(String str : list){

result.append(str).append(" ");

}

return result.toString().trim();

}

}