LeetCode 第17题电话号码的字母组合

 1 class Solution17Fix {
 2 
 3   private List<String> res = new LinkedList<>();
 4   private char[] solveArray;
 5 
 6   public List<String> letterCombinations(String digits) {
 7 
 8     if (digits == null || digits.length() == 0) {
 9       return new LinkedList<>();
10     }
11 
12     solveArray = new char[digits.length()];
13     search(0,digits);
14     return res;
15   }
16 
17   void search(int level, String digits) {
18     if (level == digits.length()) {
19       res.add(String.valueOf(solveArray));
20     } else {
21       String currString = getString(digits.charAt(level));
22       for (int i = 0; i < currString.length(); i++) {
23         solveArray[level] = currString.charAt(i);
24         search(level + 1, digits);
25       }
26     }
27   }
28 
29 
30   String getString(char c) {
31     switch (c) {
32       case ‘2‘:
33         return "abc";
34       case ‘3‘:
35         return "def";
36       case ‘4‘:
37         return "ghi";
38       case ‘5‘:
39         return "jkl";
40       case ‘6‘:
41         return "mno";
42       case ‘7‘:
43         return "pqrs";
44       case ‘8‘:
45         return "tuv";
46       case ‘9‘:
47         return "wxyz";
48       default:
49         return "";
50     }
51   }
52 }