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：查找电话号码对应的英语单词组合，可以参考《编程之美》3.2电话号码对应英语单词。主要使用递归函数的调用，找出电话号码对应的所有英语单词的组合。
class Solution { public: void RecursiveSearch(vector<string> &result,string &path,const string &digits,int index) { string str[10]={"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"}; if(index==digits.size()) { result.push_back(path); return; } for(int i=0;i<str[digits[index]-‘0‘].size();i++) { path.push_back(str[digits[index]-‘0‘][i]); RecursiveSearch(result,path,digits,index+1); path.pop_back(); } } vector<string> letterCombinations(string digits) { vector<string> result; result.clear(); string path; path.clear(); RecursiveSearch(result,path,digits,0); return result; } };
Letter Combinations of a Phone Number,布布扣,bubuko.com
Letter Combinations of a Phone Number
原文：http://www.cnblogs.com/awy-blog/p/3695716.html