Given a digit string, return all possible letter combinations that the number could represent.
A mapping of digit to letters (just like on the telephone buttons) is given below.
Input:Digit string "23" Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].
Note:
Although the above answer is in lexicographical order, your answer could be in any order you want.
1 public class Solution { 2 String[] c={ "", 3 "", 4 "abc", 5 "def", 6 "ghi", 7 "jkl", 8 "mno", 9 "pqrs", 10 "tuv", 11 "wxyz" }; 12 public List<String> letterCombinations(String digits) { 13 ArrayList<String> result = new ArrayList<String>(); 14 search(digits, 0, new StringBuilder(), result); 15 return result; 16 } 17 18 public void search(String dig, int index, StringBuilder sb, ArrayList<String> result){ 19 if(index == dig.length()){ 20 result.add(sb.toString()); 21 return; 22 } 23 int num = dig.charAt(index) - ‘0‘; 24 for(int i = 0; i < c[num].length(); i ++){ 25 StringBuilder sbs = new StringBuilder(sb); 26 sbs.append(c[num].charAt(i)); 27 search(dig, index + 1, sbs, result); 28 } 29 } 30 }
Letter Combinations of a Phone Number,布布扣,bubuko.com
Letter Combinations of a Phone Number
原文：http://www.cnblogs.com/reynold-lei/p/3894403.html