Leetcode:letter combinations of a Phone number

Title:

Given a digit string, return all possible letter combinations, the number could represent.

A mapping of Digit to letters (just as on the telephone buttons) is given below.

Input:digit string "Output": ["ad", "AE", "AF", "BD", "Be", "BF", "CD", "CE", "CF"].

A simple DFS Search

classSolution { Public: Map<int,string>Digitsmap; Solution () {digitsmap[0]=""; digitsmap[1]=""; digitsmap[2] ="ABC"; digitsmap[3] ="def"; digitsmap[4] ="Ghi"; digitsmap[5] ="JKL"; digitsmap[6] ="MnO"; digitsmap[7] ="PQRS"; digitsmap[8] ="TUV"; digitsmap[9] ="WXYZ"; } Vector<string> Lettercombinations (stringdigits) {Vector<string>result; if(digits=="")            returnresult; stringRET =""; DFS (0, Digits,ret,result); returnresult; }    voidDfsintIndexstringSstringret,vector<string>&result) {        if(Index = =s.size ())            {Result.push_back (ret); return ; }        stringTMP = digitsmap[s[index]-'0'];  for(inti =0; I < tmp.size (); i++) {ret.push_back (tmp[i]); DFS (Index+1, S,ret,result);        Ret.pop_back (); }        if(Index = =0)            return ; }};

Leetcode:letter combinations of a Phone number