Create power.cs

Math/Power/power.cs

@@ -0,0 +1,46 @@
+// Iterative C# program to 
+// compute modular power 
+class GFG 
+{ 
+
+/* Iterative Function to calculate 
+(x^y)%p in O(log y) */
+static int power(int x, int y, int p) 
+{ 
+	// Initialize result 
+	int res = 1;	 
+
+	// Update x if it is more 
+	// than or equal to p 
+	x = x % p; 
+
+	if (x == 0) 
+	return 0; 
+
+	while (y > 0) 
+	{ 
+		// If y is odd, multiply 
+		// x with result 
+		if ((y & 1) == 1) 
+			res = (res * x) % p; 
+
+		// y must be even now 
+		// y = y / 2 
+		y = y >> 1; 
+		x = (x * x) % p; 
+	} 
+	return res; 
+} 
+
+// Driver Code 
+public static void Main() 
+{ 
+	int x = 2; 
+	int y = 5; 
+	int p = 13; 
+	System.Console.WriteLine("Power is " + 
+							power(x, y, p)); 
+} 
+} 
+
+// This code is contributed by mits