KeyboardRow.java

package hashTable;

import java.util.ArrayList;
import java.util.HashMap;

/**
 * Created by cuixiaodao on 11/03/2017
 * for leetCode problem:
 * https://leetcode.com/problems/keyboard-row/description/
 */

public class KeyboardRow {
    private HashMap<Character, Integer> keyRowMap = new HashMap<Character, Integer>();

    private void init() {
        for (char c : "qwertyuiop".toCharArray()) keyRowMap.put(c, 1);
        for (char c : "asdfghjkl".toCharArray()) keyRowMap.put(c, 2);
        for (char c : "zxcvbnm".toCharArray()) keyRowMap.put(c, 3);
    }


    public String[] findWords(String[] words) {
        init();
        ArrayList<String> filteredWords = new ArrayList<String>();


        for (String w : words) {
            char[] chars = w.toLowerCase().toCharArray();

            int r = keyRowMap.get(chars[0]);
            boolean sameRow = true;
            for (char c : chars)
                if (keyRowMap.get(c) != r) {
                    sameRow = false;
                    break;
                }

            if (sameRow) filteredWords.add(w);
        }
        String[] ans = new String[filteredWords.size()];
        filteredWords.toArray(ans);
        return ans;
    }
}