Strong Number Using Indirect recursion

Java/README.md

@@ -100,6 +100,7 @@ _add list here_
 - [Sieve of Eratosthenes](math/SieveOfEratosthenes.java)
 - [Catalan Number](math/CatalanNumber.java)
 - [Palindrome Number Using Recursion](math/PalindromeRecursion.java)
+- [Strong Number Using Recursion](math/StrongRecursion.java)
 
 ## Dynamic Programming
 

Java/math/StrongRecursion.java

@@ -0,0 +1,47 @@
+//checking for a strong number using indirect recursion
+import java.util.*;
+class StrongRecursion
+{
+    public static int sofd(int n) //recursive function for sum of factorial of digits
+
+    {
+        if(n==0)
+            return n;
+        else
+            return (factorial(n%10)+sofd(n/10));
+
+    }
+
+    public static int factorial(int n) //factorial of n
+    {    
+        if (n == 0)    
+            return 1;    
+        else    
+            return(n * factorial(n-1));    
+    }    
+
+    public static void main()
+    {
+        Scanner sc=new Scanner(System.in);
+        System.out.print(" N = ");
+        int num=sc.nextInt();
+        if(num==sofd(num)) 
+            System.out.println(" It is a Strong Number");
+        else
+            System.out.println(" It is not a Strong Number");
+    }
+}
+
+/* Sample Input And Output ; 
+ * N = 145
+ * It is a Strong Number
+ * N = 534
+ *  It is not a Strong Number
+ *  
+ *  
+ *  Time Complexity : O(n)
+ *  Space Complexity : 1
+ *  
+ * 
+ */
+