Added a c++ program to find nth catalan number

02. Mathematics/5. Nth_catalan_number.cpp

@@ -0,0 +1,33 @@
+#include <iostream>
+using namespace std;
+
+/*
+    Program to find nth Catalan number
+    Constraints 1<=n<=19
+
+*/
+long catalan(int n)
+{
+    long ar[n + 1];
+
+    ar[0] = 1;
+    ar[1] = 1;
+
+    for (int i = 2; i <= n; i++) {
+        ar[i] = 0;
+        for (int j = 0; j < i; j++)
+            ar[i] += ar[j] * ar[i - j - 1];
+    }
+
+
+    return ar[n];
+}
+
+int main()
+{
+    int n;
+    cout<<"Enter the number ";
+    cin>>n;
+    cout<<"\n"<<n<<"th Catalan number is:"<<catalan(n)<<"\n";
+    return 0;
+}