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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.
用queue实现bfs:
class Solution { public: map<char,string> m; vector<string> letterCombinations(string digits) { vector<string> result; m[‘2‘]="abc"; m[‘3‘]="def"; m[‘4‘]="ghi"; m[‘5‘]="jkl"; m[‘6‘]="mno"; m[‘7‘]="pqrs"; m[‘8‘]="tuv"; m[‘9‘]="wxyz"; queue<string> q; string s; q.push(s); result = bfs(q,digits); return result; } vector<string> bfs(queue<string> q,string &digits){ vector<string> result; int len = digits.size(); if(len==0){ string s; result.push_back(s); return result; } while(!q.empty()){ string s = q.front(); int n = s.size(); q.pop(); if(n==len){ result.push_back(s); continue; } string s0(s); char c = digits[n]; int alphaNum = m[c].size(); for(int i =0;i<alphaNum;i++){ s.push_back(m[c][i]); q.push(s); s = s0; } } return result; } };
[LeetCode] Letter Combinations of a Phone Number(bfs)
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原文地址:http://www.cnblogs.com/Xylophone/p/3931560.html