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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. class Solution {
  5.     private: 
  6.     void solve(string output , vector<string>&ans , int index ,vector<string>&mapping , string &digits){
  7.         if(index>=digits.size()){
  8.             ans.push_back(output);
  9.             return;
  10.         }
  11.         int number = digits[index] - '0';
  12.         if (number < 2 || number >9){
  13.             return;
  14.         }
  15.         string values = mapping[number];
  16.         for(char c : values){
  17.             output.push_back(c);
  18.             solve(output , ans , index+1, mapping , digits);
  19.             output.pop_back();
  20.         }
  21.     }
  22. public:
  23.     vector<string> letterCombinations(string digits) {
  24.         if(digits.empty()) return {};
  25.         string output = "";
  26.         int index = 0;
  27.         vector<string>ans;
  28.         vector<string>mapping = {" ", " ", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
  29.         solve(output,ans,index,mapping,digits);
  30.         return ans;
  31.     }
  32. };
  33.  
  34. int main() {
  35.     Solution sol;
  36.  
  37.     // Input string for which we want to compute combinations
  38.     string digits = "23";
  39.  
  40.     // Call the method to get the letter combinations
  41.     vector<string> result = sol.letterCombinations(digits);
  42.  
  43.     // Output the result
  44.     cout << "Letter Combinations for input \"23\":\n";
  45.     for (const string& str : result) {
  46.         cout << str << " ";
  47.     }
  48.     cout << endl;
  49.  
  50.     return 0;
  51. }
  52.  
Success #stdin #stdout 0s 5280KB
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Standard input is empty
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Letter Combinations for input "23":
ad ae af bd be bf cd ce cf
https://ideone.com/tTK4u2
language:
C++ (gcc 8.3)
created:
11 days ago
visibility:
public

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