[Leetcode]Letter Combinations of a phone number

//和combination sum很像，就是多一个dictionary

class Solution {

const vector<string> yang=

{

" ",

"",

"abc",

"def",

"ghi",

"jkl",

"mno",

"pqrs",

"tuv",

"wxyz"

};

public:

vector<string> letterCombinations(string digits) {

vector<string> result;

string temp="";

dfs(digits,0,temp,result);

return result;

}

void dfs(const string &digits,int cur,string temp,vector<string>&result)

{

if(cur==digits.size())

{

result.push_back(temp);

return;

}

for(int i=0;i<yang[digits[cur]-'0'].size();i++)

{

temp=temp+yang[digits[cur]-'0'][i];

dfs(digits,cur+1,temp,result);

temp.pop_back();

}

}

};