CODE EXAMPLE FOR CSHARP

generic binary search c#

using System;
					
public class Program
{
	public static void Main()
	{
		int[] arr = new int[] {1, 2, 3, 4, 4, 5, 6, 7, 7, 7, 7, 8};
		int query = 7;
		Console.WriteLine(Find(arr, query));
		Console.WriteLine(FindLeft(arr, query));
		Console.WriteLine(FindRight(arr, query));
	}
	public delegate string Condition(int mid);
    public static int GenericBinarySearch(int lo, int hi, Condition cond)
	{
		while(lo<=hi)
		{ 
			int mid = (lo+hi)/2;
			string result = cond(mid);
			if(result=="found") return mid;
			else if(result=="left") hi = mid-1;
			else lo=mid+1;
		}
		return -1;
	}
	public static int Find(int[] arr, int query)
	{
		int lo = 0;
		int hi = arr.Length-1;
		string CondLeft(int mid)
		{
			if(arr[mid]==query)
			{
				return "found";
			}
			else if(arr[mid]>query) 
			{
				return "left";
			}
			else return "right";
		}
		return GenericBinarySearch(lo, hi, CondLeft);
	}
	public static int FindLeft(int[] arr, int query)
	{
		int lo = 0;
		int hi = arr.Length-1;
		string CondLeft(int mid)
		{
			if(arr[mid]==query)
			{
				if(mid-1>0 && arr[mid-1]==query) return "left";
				return "found";
			}
			else if(arr[mid]>query) 
			{
				return "left";
			}
			else return "right";
		}
		return GenericBinarySearch(lo, hi, CondLeft);
	}
	public static int FindRight(int[] arr, int query)
	{
		int lo = 0;
		int hi = arr.Length-1;
		string CondLeft(int mid)
		{
			if(arr[mid]==query)
			{
				if(mid+1<arr.Length && arr[mid+1]==query) return "right";
				return "found";
			}
			else if(arr[mid]>query) 
			{
				return "left";
			}
			else return "right";
		}
		return GenericBinarySearch(lo, hi, CondLeft);
	}
}