水题。数字一共就9个,去掉1是用来显示标点的,剩下8个。
穷举一下map,然后有几个数字,就输出这几个数字的排列,是一个dfs嘛。
map<char, string> num; void allCombinations(string &digits, int start, int len, string &pres, vector<string> &res){ if(len == digits.length()){ res.push_back(pres); //cout<<pres<<endl; return; } for(int i=0;i<num[digits[start]].length();i++){ pres[len] = num[digits[start]][i]; allCombinations(digits, start+1, len+1, pres, res); } } class Solution { public: vector<string> letterCombinations(string digits) { vector<string> res; if(digits.length()<=0){ res.push_back(""); return res; } num[‘2‘] = "abc"; num[‘3‘] = "def"; num[‘4‘] = "ghi"; num[‘5‘] = "jkl"; num[‘6‘] = "mno"; num[‘7‘] = "pqrs"; num[‘8‘] = "tuv"; num[‘9‘] = "wxyz"; string pres(digits.length(),‘#‘); allCombinations(digits, 0, 0, pres, res); return res; } };
leetcode第一刷_Letter Combinations of a Phone Number,布布扣,bubuko.com
leetcode第一刷_Letter Combinations of a Phone Number
原文地址:http://blog.csdn.net/u012792219/article/details/25832399