Exercise_1.cs

// Time Complexity
// Best Case - O(1)
// Average Case - O(log n)
// Worst Case - O(log n)

// Space Complexity
// O(1)
public class BinarySearch
{
    // Returns index of x if it is present in arr[l.. r], else return -1 
    public int binarySearch(int[] arr, int l, int r, int x)
    {
        //Write your code here
        while (l <= r)
        {
            int mid = l + (r - l) / 2;
            if (arr[mid] == x)
            {
                return mid;
            }
            else if (arr[mid] > x)
            {
                r = mid - 1;
            }
            else
            {
                l = mid + 1;
            }
        }
        return -1;
    }

    // Driver method to test above 
    public static void Main(String[] args)
    {
        BinarySearch ob = new BinarySearch();
        int[] arr = { 2, 3, 4, 10, 40 };
        int n = arr.Length;
        int x = 10;
        int result = ob.binarySearch(arr, 0, n - 1, x);
        if (result == -1)
            Console.WriteLine("Element not present");
        else
            Console.WriteLine("Element found at index " + result);
    }
}