Ugly Number With Recursion (Addition of Ugly Number Problem #1286)

Java/README.md

@@ -44,6 +44,8 @@ _add list here_
 - [Happiness Problem (cp sets question)](cp/HappinessProblem.java)
 - [Prime Number With Recursion](cp/PrimeRecursion.java)
 - [Prime Number without Recursion](cp/Prime.java)
+- [Ugly Number With Recursion](cp/UglyRecursion.java) 
+- [PDDI Using Recursion](cp/ArmStrongRecursion.java)
 
 ## Cryptography
 

Java/cp/ArmStrongRecursion.java

@@ -0,0 +1,33 @@
+// Checking Armstrong number with Recursion
+
+import java.util.Scanner;
+class ArmStrongRecursion
+{
+    static int p;
+    public static int armstrong(int i)
+    { if(i<10) //base class
+        return (int)(Math.pow(i,p));
+        else
+        return((int)Math.pow(i%10,p)+armstrong(i/10));
+    }
+    public static void main(String args[])
+    {
+        Scanner sc=new Scanner(System.in);
+        System.out.print("N = ");
+        int n=sc.nextInt();
+        p=Integer.toString(n).length(); //calculating the number of digits in the number by converting it into String
+
+        if(n==armstrong(n))
+        System.out.println(n+" is an Armstrong number");
+        else
+        System.out.println(n+" is not an Armstrong number");
+    }
+}
+
+/*
+Sample Input and Output :
+N = 153
+153 is an Armstrong number
+Space Complexity: O(1)
+Time Complexity : O(p)
+*/

Java/cp/UglyRecursion.java

@@ -0,0 +1,48 @@
+//finding nth ugly number using recursion
+import java.util.Scanner;
+class UglyRecursion
+{
+
+       public static int ugly(int n) 
+    { 
+
+        if (n == 1)  //base cases
+            return 1; 
+        if (n <= 0) 
+            return 0; 
+        if (n % 2 == 0)  
+            return (ugly(n / 2)); 
+
+        if (n % 3 == 0) 
+            return (ugly(n / 3)); 
+
+        if (n % 5 == 0)  
+            return (ugly(n / 5)); 
+
+        return 0; 
+    } 
+
+
+
+    public static void main(String args[])
+    {
+        Scanner sc=new Scanner(System.in);
+        System.out.print("N= ");
+        int n=sc.nextInt();
+        int i=1;
+        while(n>0)
+        { if(ugly(i)==1)
+            n-=1;
+            i++;
+        }
+        System.out.println(i--); //to avoid the last increment,we decrement by one
+    }
+}
+
+
+/* Sample Input
+   Input:
+N = 10
+Output: 12
+Time Complexity : O(n)
+Space Complexity : O(1)*/

Java/math/ArmStrongRecursion.java

@@ -0,0 +1,33 @@
+// Checking Armstrong number with Recursion
+
+import java.util.Scanner;
+class ArmStrongRecursion
+{
+    static int p;
+    public static int armstrong(int i)
+    { if(i<10) //base class
+        return (int)(Math.pow(i,p));
+        else
+        return((int)Math.pow(i%10,p)+armstrong(i/10));
+    }
+    public static void main(String args[])
+    {
+        Scanner sc=new Scanner(System.in);
+        System.out.print("N = ");
+        int n=sc.nextInt();
+        p=Integer.toString(n).length(); //calculating the number of digits in the number by converting it into String
+
+        if(n==armstrong(n))
+        System.out.println(n+" is an Armstrong number");
+        else
+        System.out.println(n+" is not an Armstrong number");
+    }
+}
+
+/*
+Sample Input and Output :
+ N = 153
+153 is an Armstrong number
+Space Complexity: O(1)
+Time Complexity : O(p)
+*/