LeetCode17 电话号码的字母组合
前言
题目: 17. 电话号码的字母组合
文档: 代码随想录——电话号码的字母组合
编程语言: C++
解题状态: 没搞出来…
思路
还是回溯的路子,不过关键在于找到总的集合,在这个大集合里面进行回溯,本题的大集合就比较隐蔽,不太容易发现。
代码
class Solution {
private:const string letterMap[10] = {"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz",};
public:vector<string> res;string s;void backtracking(const string& digits, int index) {if (index == digits.size()) {res.push_back(s);return;}int digit = digits[index] - '0';string letters = letterMap[digit];for (int i = 0; i < letters.size(); i++) {s.push_back(letters[i]);backtracking(digits, index + 1);s.pop_back();}}vector<string> letterCombinations(string digits) {s.clear();res.clear();if (digits.size() == 0) {return res;}backtracking(digits, 0);return res;}
};