Solution: Find the Peak Element

using System;
class Program
{
    /// <summary>
    /// Finds a peak element in a array of integers.
    /// </summary>
    /// <param name="arr">Array of integers.</param>
    /// <returns>A peak element in the given array.</returns>
    public static int FindPeak(int[] arr)
    {
        // If the array is empty
        if (arr.Length == 0)
        {
            return -1;
        }
        // If the array has only one element
        if (arr.Length == 1)
        {
            return arr[0];
        }
        for (int i = 1; i < arr.Length - 1; i++)
        {
            if (arr[i] >= arr[i - 1] && arr[i] >= arr[i + 1])
            {
                return arr[i];
            }
        }
        if (arr[0] >= arr[1])
        {
            return arr[0];
        }
        else if (arr[arr.Length - 1] >= arr[arr.Length - 2])
        {
            return arr[arr.Length - 1];
        }
        return -1;
    }
    // Driver code to test the above method
    public static void Main(string[] args)
    {
        // Example 1
        int[] arr1 = { 7, 11, 22, 13, 4, 0 };
        Console.WriteLine("One peak point is: " + FindPeak(arr1));
        // Example 2
        int[] arr2 = { 0, 3, 100, 2, -1, 0 };
        Console.WriteLine("One peak point is: " + FindPeak(arr2));
        // Example 3
        int[] arr3 = { 6, 5, 4, 3, 2, 1 };
        Console.WriteLine("One peak point is: " + FindPeak(arr3));
    }
}

using System;
class Program
{
    /// <summary>
    /// Finds a peak element in a array of integers within a specified range.
    /// </summary>
    /// <param name="low">Starting index of the array.</param>
    /// <param name="high">Ending index of the array.</param>
    /// <param name="arr">Array of integers.</param>
    /// <returns>A peak element in the given array within the specified range.</returns>
    public static int FindPeakRecursive(int low, int high, int[] arr)
    {
        // Finding the middle index
        int middle = low + (high - low) / 2;
        // If middle element is a peak
        if ((middle == arr.Length - 1 || arr[middle + 1] <= arr[middle]) &&
            (middle == 0 || arr[middle - 1] <= arr[middle]))
        {
            return middle;
        }
        // If left neighbor is greater, then peak is in the left half
        if (middle > 0 && arr[middle - 1] > arr[middle])
        {
            return FindPeakRecursive(low, middle - 1, arr);
        }
        // If right neighbor is greater, then peak is in the right half
        return FindPeakRecursive(middle + 1, high, arr);
    }
    /// <summary>
    /// Finds a peak element in a array of integers.
    /// </summary>
    /// <param name="arr">Array of integers.</param>
    /// <returns>A peak element in the given array.</returns>
    public static int FindPeak(int[] arr)
    {
        return arr[FindPeakRecursive(0, arr.Length - 1, arr)];
    }
    // Driver code to test the above method
    public static void Main(string[] args)
    {
        // Example 1
        int[] arr1 = { 7, 11, 22, 13, 4, 0 };
        Console.WriteLine("One peak point is: " + FindPeak(arr1));
        // Example 2
        int[] arr2 = { 0, 3, 100, 2, -1, 0 };
        Console.WriteLine("One peak point is: " + FindPeak(arr2));
        // Example 3
        int[] arr3 = { 6, 5, 4, 3, 2, 1 };
        Console.WriteLine("One peak point is: " + FindPeak(arr3));
    }
}