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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.
[Solution]
递归求解。
1 const string dict[10] = {"", " ", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"}; 2 vector<string> letterCombinations(string digits) 3 { 4 vector<string> result; 5 if (digits.size() == 0) 6 return result; 7 string line; 8 proceed(result, line, digits, 0); 9 10 return result; 11 } 12 13 void proceed(vector<string> &result, string &line, const string &digits, int steps) 14 { 15 if(steps == digits.size()) 16 { 17 result.push_back(line); 18 return; 19 } 20 21 for (int i = 0; i < dict[digits[steps] - ‘0‘].size(); i++) 22 { 23 line.push_back(dict[digits[steps] - ‘0‘][i]); 24 proceed(result, line, digits, steps + 1); 25 line.pop_back(); 26 } 27 }
[*leetcode 17] Letter Combinations of a Phone Number
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原文地址：http://www.cnblogs.com/ym65536/p/4382162.html
