Binary Search | Phaisarn Sutheebanjard

ค้นหาจากตำแหน่งกึ่งกลาง ถ้าเจอก็จบ
ถ้าไม่เจอ แล้วเลขที่ค้นหามีค่ามากกว่า ก็หาต่อทางครึ่งซ้าย
ถ้าไม่เจอ แล้วเลขที่ค้นหามีค่าน้อยกว่า ก็หาต่อทางครึ่งขวา

โค๊ด

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            // declare an array of integers that will be used for searching
            int[] arrLinearSearch = { 2, 3, 4, 5, 8, 10 };
            int searchTerm = 8;
            int result = BinarySearch(arrLinearSearch, searchTerm, 0, arrLinearSearch.Length - 1);

            if (result != -1)
            {
                Console.WriteLine($"Search term found at index {result}.");
            }
            else
            {
                Console.WriteLine("Search term not found in the array.");
            }
        }

        public static int BinarySearch(int[] arr, int key, int first, int last)
        {
            while (first <= last)
            {
                int mid = (first + last) / 2;
                if (key == arr[mid])
                {
                    return mid;
                }
                else if (key < arr[mid])
                {
                    last = mid - 1;
                }
                else
                {
                    first = mid + 1;
                }
            }
            return -1;
        }
    }
}

using System;

namespace ConsoleApp1

{

class Program

{

static void Main(string[] args)

{

// declare an array of integers that will be used for searching

int[] arrLinearSearch = { 2, 3, 4, 5, 8, 10 };

int searchTerm = 8;

int result = BinarySearch(arrLinearSearch, searchTerm, 0, arrLinearSearch.Length - 1);

if (result != -1)

{

Console.WriteLine($"Search term found at index {result}.");

}

else

{

Console.WriteLine("Search term not found in the array.");

}

public static int BinarySearch(int[] arr, int key, int first, int last)

{

while (first <= last)

{

int mid = (first + last) / 2;

if (key == arr[mid])

{

return mid;

}

else if (key < arr[mid])

{

last = mid - 1;

}

else

{

first = mid + 1;

}

return -1;

}

ผลการรัน
[code]
Search term found at index 4.
Press any key to continue . . .
[/code]