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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"].
简单的DFS搜索
class Solution { 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(string digits) { vector<string> result; if (digits=="") return result; string ret = ""; dfs(0,digits,ret,result); return result; } void dfs(int index, string s, string ret,vector<string>& result){ if (index == s.size()){ result.push_back(ret); return ; } string tmp = digitsMap[s[index]-‘0‘]; for (int i = 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
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原文地址：http://www.cnblogs.com/yxzfscg/p/4421292.html
