## Monday, December 24, 2012

### [LeetCode] Letter Combinations of a Phone Number 解题报告

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.
» Solve this problem

[解题思路]

[Code]
``````1:    vector<string> letterCombinations(string digits) {
2:      // Start typing your C/C++ solution below
3:      // DO NOT write int main() function
4:      string trans[] = {"", " ", "abc", "def", "ghi", "jkl",
5:        "mno", "pqrs", "tuv", "wxyz"};
6:      vector<string> set;
7:      string seq;
8:      Generater(trans, digits, 0, seq, set);
9:      return set;
10:    }
11:    void Generater(string trans[], string& digits,
12:      int deep, string& result, vector<string>& set)
13:    {
14:      if(deep == digits.size())
15:      {
16:        set.push_back(result);
17:        return;
18:      }
19:      int curDig = digits[deep] - 48;
20:      for(int i =0; i < trans[curDig].size(); i++)
21:      {
22:        result.push_back(trans[curDig][i]);
23:        Generater(trans, digits, deep+1, result, set);
24:        result.resize(result.size() -1);
25:      }
26:    }
``````

[注意]
1. Line 19。ACSII码转int要减去48.