package Recursion;

import javax.lang.model.util.Types;

import java.util.*;

public class HotKeys {

/**

* Given a list of strings, assign a unique character as a hotkey.

* 1. Hotkey of a string should be a character of the string

* 2. All hotkeys must be unique

*

* Ex['front', 'back', 'left', 'right', 'fly']

* Output [f, b, l, r, y]

*

* ["forward", "backward", "left", "right", "fly", "flye", "flyee"]

* [f,b,t,l,y,e]

*/

public static Map<Character, String> hotKeys(List<String> input){

Map<Character, String> result = new HashMap<>();

helper(input, 0, result);

return result;

}

private static void helper(List<String> input, int index,

Map<Character, String> result ) {

if (index == input.size()) {

return;

}

else {

String s = input.get(index);

for (int i =0; i < s.length(); i++){

char c = s.charAt(i);

if (! result.containsKey(c)){

result.put(c, s);

helper(input, index+1, result);

if(result.size() == input.size())

break;

result.remove(c);

}

}

}

}

public static void main(String args[]){

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

input.add("forward");

input.add("left");

input.add("fly");

input.add("flye");

input.add("flyee");

input.add("flyeee");

System.out.println(hotKeys(input));

}

}