FindElementInAscendingSortedRotatedArray, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            int[] arr = new int[] {5,6,7,8,9,1,2,3};
            int key=9;
            int n= arr.Length-1;
            
            Boolean found = findElementInAscSortedRotatedArray(arr, key, n);
            Console.Write("Found " + found);
        }
        
        public static Boolean findElementInAscSortedRotatedArray(int[] arr, int key, int n)
        {
            
            if((n == 0) || (n == null))
                return false;

if(key < arr[0])
             {
                 for(int i = n; i>0; i--)
                 {
                     if(key == arr[i])
                     {
                         Console.Write("Index " + i);
                         return true;
                     }
                 }
             }
            
             if(key > arr[0])
             {
                 for(int i = 0; i<n; i++)
                 {
                     if(key == arr[i])
                     {
                         Console.Write("Index " + i);
                         return true;
                     }
                 }
             } 
                
            return false;
            
        }
    }
}

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Compilation time: 0,14 sec, absolute running time: 0,09 sec, cpu time: 0,09 sec, average memory usage: 14 Mb, average nr of threads: 3