Catalan code added

Author: sharur7

Diff for: C-Sharp/README.md

@@ -48,6 +48,7 @@ _add list here_
 
 - [Finding no of digits in an integer](math/Finding_no_of_digits_in_an_integer.cs)
 - [Tower of Hanoi](math/tower_of_hanoi.cs)
+- [Catalan Number](math/Catalan_Number.cs)
 
 ## Other
 

Diff for: C-Sharp/math/Catalan_Number.cs

@@ -0,0 +1,44 @@
+// Nth Catalan Number 
+using System; 
+class CatalanNumber 
+{ 
+    // A recursive function to find 
+    // nth catalan number 
+    static int catalan(int n) 
+    { 
+        int res = 0; 
+        
+        // Base case 
+        if (n <= 1) 
+        { 
+            return 1; 
+        } 
+        for (int i = 0; i < n; i++) 
+        {
+            res += catalan(i) * catalan(n - i - 1); 
+        } 
+        return res; 
+    } 
+    
+    // Main Function
+    public static void Main() 
+    { 
+        int number;
+        Console.Write("Enter the Number: ");
+        number = int.Parse(Console.ReadLine());
+        Console.Write("Nth Catalan numbers are: ");
+        // Catalan Numbers
+        for (int i = 0; i < number; i++) 
+            Console.Write(catalan(i) + " "); 
+    } 
+} 
+
+/*
+Input:
+Enter the Number: 4
+Output:
+Nth Catalan numbers are: 1 1 2 5
+
+Time Complexity: O(2^n)
+Space Complexity: O(1)
+*/