# Concatenated Words

This page explains Java solution to problem `Concatenated Words` using `Dynamic Programming` algorithm.

## Problem Statement

Given a list of words (without duplicates), please write a program that returns all concatenated words in the given list of words.

A concatenated word is defined as a string that is comprised entirely of at least two shorter words in the given array.

Example 1:

Input: ["cat","cats","catsdogcats","dog","dogcatsdog","hippopotamuses","rat","ratcatdogcat"]
Output: ["catsdogcats","dogcatsdog","ratcatdogcat"]
Explanation:
"catsdogcats" can be concatenated by "cats", "dog" and "cats";
"dogcatsdog" can be concatenated by "dog", "cats" and "dog";
"ratcatdogcat" can be concatenated by "rat", "cat", "dog" and "cat"

## Solution

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``````
package com.vc.hard;

import java.util.*;

class ConcatenatedWords {
Arrays.sort(words, new Comparator<String>(){
public int compare(String s1, String s2) {
return Integer.compare(s1.length(), s2.length());
}
});

HashSet<String> set = new HashSet<>();
List<String> res = new ArrayList<>();
for(String word: words) {
}
return res;
}

private boolean canForm(String word, HashSet<String> set) {
if(set.isEmpty()) return false;
int n = word.length();
boolean[] dp = new boolean[n + 1];
dp = true;
for(int i = 1; i <= word.length(); i++) {
for(int j = 0; j < i; j++) {
if(dp[j] && set.contains(word.substring(j, i))) {
dp[i] = true;
break;
}
}
}
return dp[n];
}
}
``````

## Time Complexity

O(N * K2) Where
N is total number of elements in an input string array words
K is length of longest word in an input array

## Space Complexity

O(N) Where
N is total number of elements in an input string array words