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.

Example 1:

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

 

Note:

1. You may use one character in the keyboard more than once.
2. You may assume the input string will only contain letters of alphabet.

 

 

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题目标签：Hash Table

　　题目给了我们一个words array，让我们判断每一个word 中的 chars 是否都来自于键盘上的同一行。

　　利用HashMap 把键盘上的3行 chars 保存：char 当作 key；行数 当作 value。

　　接着遍历words，检查每一个word。

 

 

Java Solution:

Runtime beats 68.36% 

完成日期：06/07/2017

关键词：HashMap

关键点：char 当作 key；行数 当作 value

1 class Solution  2 { 3     public String[] findWords(String[] words)  4     { 5         HashMap
      
        map = new HashMap<>(); 6         List
       
         resList = new ArrayList<>(); 7          8         String row1 = "qwertyuiop"; 9         String row2 = "asdfghjkl";10         String row3 = "zxcvbnm";11         12         // set up the map13         for(char c: row1.toCharArray())14             map.put(c, 1);15         16         for(char c: row2.toCharArray())17             map.put(c, 2);18         19         for(char c: row3.toCharArray())20             map.put(c, 3);21         22         23         // iterate each word to check all chars are from one row24         for(String word: words)25         {26             char[] wordChars = word.toLowerCase().toCharArray();27             int rowNumber = map.get(wordChars[0]);28             boolean add = true;29             30             for(char c: wordChars)31             {32                 if(rowNumber != map.get(c))33                 {34                     add = false;35                     break;36                 }37                    38             }39             40             if(add)41                 resList.add(word);42         }43         44         String[] res = new String[resList.size()];45         46         for(int i=0; i
       
      

参考资料：N/A　　

 

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