#ifndef S0017_LETTER_COMBINATIONS_OF_A_PHONE_NUMBER_HPP
#define S0017_LETTER_COMBINATIONS_OF_A_PHONE_NUMBER_HPP
#include <vector>
#include <string>
#include <unordered_map>
using namespace std;
class Solution {
public:
vector<string> letterCombinations(string digits);
};
#endif