标签：style blog http color os io ar for 2014
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.
string choices[] = {" ", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
vector<string> res;
string _digits;
void dfs(string str, int cur){
if(cur == _digits.size()){
res.push_back(str);
return ;
}
string choice = choices[_digits[cur] - '0'];
for_each(choice.begin(), choice.end(), [&](char c){
dfs(str + c, cur + 1);
//回溯 --> 因为 str和 cur的值没改，所以不用
});
}
vector<string> letterCombinations(string digits){
_digits = digits;
dfs("", 0);
return res;
}
Leetcode dfs Letter Combinations of a Phone Number
标签：style blog http color os io ar for 2014
原文地址：http://blog.csdn.net/zhengsenlie/article/details/39137443
