Leetcode- keyboard line - simple

title ：500 Keyboard line - Simple

subject

Here's an array of strings words , Returns only those that can be used in American keyboard Words printed with letters on the same line .

• The first line consists of the characters "qwertyuiop" form .
• The second line consists of characters "asdfghjkl" form .
• The third line consists of the characters "zxcvbnm" form .

Example 1

 Input ：words = ["Hello","Alaska","Dad","Peace"]
 Output ：["Alaska","Dad"]

Example 2

 Input ：words = ["omk"]
 Output ：[]

Example 3

 Input ：words = ["adsdf","sfd"]
 Output ：["adsdf","sfd"]

Tips

• 1 <= words.length <= 20
• 1 <= words[i].length <= 100
• words[i] By the English letters （ Lower and upper case letters ） form

Code Java

public String[] findWords(String[] words) {
    
    StringBuilder ans = new StringBuilder();
    int[] rows = {
    2,3,3,2,1,2,2,2,1,2,2,2,3,3,1,1,1,1,2,1,1,3,1,3,1,3};
    int index;
    for (int i = 0; i < words.length; i++) {
    
        String s = words[i].toLowerCase();
        int count = rows[s.charAt(0) - 97];
        int j;
        for (j = 0; j < s.length(); j++) {
    
            index = s.charAt(j) - 97;
            if (rows[index] != count)
                break;
        }
        if (j == s.length()) {
    
            ans.append(words[i]);
            ans.append("-");
        }
    }
    String[] str = ans.toString().split("-");
    if (str[0].length() == 0) {
    
        String[] strNull = new String[0];
        return strNull;
    }
    return str;
}