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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.
思路：
又是dfs的题目，dfs的时候，注意string一定要清除本次添加的元素。
题解：
class Solution { public: vector<string> res; string tmp; void dfs(string digits, int index, string board[]) { if(index==digits.size()) { res.push_back(tmp); return; } string str = board[digits[index]-‘0‘]; for(int i=0;i<str.size();i++) { tmp.push_back(str[i]); dfs(digits, index+1, board); tmp.pop_back(); } } vector<string> letterCombinations(string digits) { string board[] = {"0", "1", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz",}; dfs(digits,0, board); return res; } };
后话：
每次这种题目我都是用的dfs，自己都烦了。来看看其他的牛逼方法吧。等着我在刷这题的时候尝试一下其他思路。
[leetcode] Letter Combinations of a Phone Number
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原文地址：http://www.cnblogs.com/jiasaidongqi/p/4221033.html
