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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"].Note:
Although the above answer is in lexicographical order, your answer could be in any order you want.
下面是我AC的代码：
/** * author:Zhou J */
class Solution { public: vector<string> letterCombinations(string digits) { map<char, string> digitToString; digitToString.insert(make_pair(‘0‘, "")); digitToString.insert(make_pair(‘1‘, "")); digitToString.insert(make_pair(‘2‘, "abc")); digitToString.insert(make_pair(‘3‘, "def")); digitToString.insert(make_pair(‘4‘, "ghi")); digitToString.insert(make_pair(‘5‘, "jkl")); digitToString.insert(make_pair(‘6‘, "mno")); digitToString.insert(make_pair(‘7‘, "pqrs")); digitToString.insert(make_pair(‘8‘, "tuv")); digitToString.insert(make_pair(‘9‘, "wxyz")); vector<string> ret; string path; letterCombinationsRec(digits, ret, path, digitToString); return ret; } void letterCombinationsRec(const string &digits, vector<string> &ret, string &path, map<char, string> &digitToString) { if (path.size() == digits.size()) { ret.push_back(path); return; } for(const auto &digit : digitToString[digits[path.size()]]) { path.push_back(digit); letterCombinationsRec(digits, ret, path, digitToString); path.erase(path.size() - 1); } } };
[LeetCode] Letter Combinations of a Phone Number
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原文地址：http://www.cnblogs.com/jianxinzhou/p/4190014.html
