return keypad

Author: anmolpant

Diff for: Data Structures in Java/Level 1/Lecture 4 - Recursion 2/Recursion2_ReturnKeypadCode.java

@@ -0,0 +1,80 @@
+
+public class Recursion2_ReturnKeypadCode {
+	
+	public static String[] keypad(int n){
+		// Write your code here
+        
+        if (n==0){
+            String ans[] = {""};
+            return ans;
+        }
+        
+        
+        String[] smallAns = keypad(n/10);
+        String[] options = keymap(n%10);
+        
+        String ans[] = new String[smallAns.length * options.length];
+        
+        int k = 0;
+        for (int i = 0; i<smallAns.length;i++){
+            //ans[i] = smallAns[i];
+            for(int j = 0; j<options.length; j++){
+                ans[k] = smallAns[i] + options[j];
+                k++;
+            }
+        }
+        
+        return ans;
+
+	}
+    
+    
+    private static String[] keymap(int n){
+        if (n==0 || n==1){
+            String ans[] = {""};
+            return ans;
+        }
+        
+        else if (n==2){
+            String ans[] = {"a","b","c"};
+            return ans;
+        }
+        
+        else if (n==3){
+            String ans[] = {"d","e","f"};
+            return ans;
+        }
+        
+        else if(n==4){
+            String ans[] = {"g","h","i"};
+            return ans;
+        }
+        
+        else if(n==5){
+            String ans[] = {"j","k","l"};
+            return ans;
+        }
+        
+        else if(n==6){
+            String ans[] = {"m","n","o"};
+            return ans;
+        }
+        
+        else if(n==7){
+            String ans[] = {"p","q","r","s"};
+            return ans;
+        }
+        
+        else if(n==8){
+            String ans[] = {"t","u","v"};
+            return ans;
+        }
+        
+        else if(n==9){
+            String ans[] = {"w","x","y","z"};
+            return ans;
+        } 
+        return null;
+    }
+
+}