Merge pull request #515 from paurush11/master

Possible Words From Phone Digits

Author: smv1999

Recursion/Possible_Words_From_Phone_Digits.cpp

@@ -0,0 +1,115 @@
+/*
+Possible Words From Phone Digits
+Medium Accuracy: 51.47% Submissions: 11922 Points: 4
+Given a keypad as shown in the diagram, and an N digit number which is represented by array a[ ], the task is to list all words which are possible by pressing these numbers.
+
+
+Example 1:
+
+Input: N = 3, a[] = {2, 3, 4}
+Output:
+adg adh adi aeg aeh aei afg afh afi
+bdg bdh bdi beg beh bei bfg bfh bfi
+cdg cdh cdi ceg ceh cei cfg cfh cfi
+Explanation: When we press 2,3,4 then
+adg, adh, adi, ... cfi are the list of
+possible words.
+Example 2:
+
+Input: N = 3, a[] = {3, 4, 5}
+Output:
+dgj dgk dgl dhj dhk dhl dij dik dil
+egj egk egl ehj ehk ehl eij eik eil
+fgj fgk fgl fhj fhk fhl fij fik fil
+Explanation: When we press 3,4,5 then
+dgj, dgk, dgl, ... fil are the list of
+possible words.
+Your Task:
+You don't need to read input or print anything. You just need to complete the function possibleWords() that takes an array a[ ] and N as input parameters and returns an array of all the possible words in lexicographical increasing order.
+
+Expected Time Complexity: O(4N * N).
+Expected Auxiliary Space: O(N).
+
+Constraints:
+1 ≤ N ≤ 10
+2 ≤ a[i] ≤ 9
+*/
+
+//Initial Template for C++
+
+#include <bits/stdc++.h>
+#include <string>
+
+using namespace std;
+
+
+ // } Driver Code Ends
+//User function Template for C++
+
+class Solution
+{
+    public:
+    //Function to find list of all words possible by pressing given numbers.
+
+
+    void formstring(int a[], int N, string s, vector<string>&v, int i,map<int, vector<char>>m){
+        if(i == N){
+            v.push_back(s);
+            return;
+        }
+        int pos = a[i];
+        for(auto j : m[pos]){
+            formstring(a,N,s+j,v,i+1,m);
+        }
+    }
+    vector<string> possibleWords(int a[], int N)
+    {
+        map<int, vector<char>>m;
+        int k = 0;
+        for(int i = 2;i<=6;i++){
+            int j = 0;
+            while(j<3){
+                m[i].push_back('a'+ j + k);
+                j++;
+            }
+            k+=3;
+        }
+        m[7] = {'p','q','r','s'};
+        m[8] = {'t','u','v'};
+        m[9] = {'w','x','y','z'};
+
+        vector<string>ans;
+        formstring(a,N,"",ans,0,m);
+        return ans;
+    }
+};
+
+
+// { Driver Code Starts.
+
+int main() {
+
+	int T;
+
+	cin >> T; //testcases
+
+	while(T--){ //while testcases exist
+	   int N;
+
+	   cin >> N; //input size of array
+
+	   int a[N]; //declare the array
+
+	   for(int i =0;i<N;i++){
+	       cin >> a[i]; //input the elements of array that are keys to be pressed
+	   }
+
+	   Solution obj;
+
+	  vector <string> res = obj.possibleWords(a,N);
+	  for (string i : res) cout << i << " ";
+	   cout << endl;
+	}
+
+	return 0;
+}  // } Driver Code Ends