package com.leetcode.string;

import java.util.*;

import java.util.stream.Stream;

/**

* Created by charles on 3/23/17.

* Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.

* Input: ["Hello", "Alaska", "Dad", "Peace"]

* Output: ["Alaska", "Dad"]

*/

public class KeyboardRow_500 {

private char[][] rows = {{'q','w','e','r','t','y','u','i','o','p'},

{'a','s','d','f','g','h','j','k','l'},

{'z','x','c','v','b','n','m'}};

private Map<Character, Integer> map = generateMap();

public String[] findWords(String[] words) {

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

for (String w : words) {

if (testWord(w.toLowerCase())) {

res.add(w);

}

}

return res.toArray(new String[0]);

}

private Map<Character, Integer> generateMap() {

Map<Character, Integer> dict = new HashMap<>();

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

for (char c : rows[i]) {

dict.put(c, i);

}

}

return dict;

}

private boolean testWord(String word) {

int i = 1;

int len = word.length();

while (i < len) {

if (map.get(word.charAt(i)) != map.get(word.charAt(i-1))) {

return false;

}

i++;

}

return true;

}

public static void main(String[] args) {

KeyboardRow_500 k = new KeyboardRow_500();

String[] w1 = {"Hello", "Alaska", "Dad", "Peace"};

String[] res = k.findWords(w1);

output(res);

String[] res1 = k.findWordsII(w1);

output(res1);

}

private static void output(String[] res) {

Arrays.asList(res).stream().forEach(t -> System.out.print(t + ","));

System.out.println();

}

/** Single one line solution using Lambda */

public String[] findWordsII(String[] words) {

String regex = "[qwertyuiop]*|[asdfghjkl]*|[zxcvbnm]*";

return Stream.of(words).filter(s -> s.toLowerCase().matches(regex)).toArray(String[]::new);

// String[]::new is a syntax sugar for lambda expression size -> new String[size]

}

}