利用递归实现折半查找

static void Main(string[] args)

{

int[] array = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

int index = BinarySearch(array, 0, array.Length,5);

Console.WriteLine(index);

}

//利用递归实现折半查找

注意集合一定是要有序的，如果不是要对集合西先进行排序然后在查找

public static int BinarySearch(int[] arr, int low, int high, int key)

{

Console.WriteLine(“——-“);

int mid = (low + high) / 2;

if (low > high)

return -1;

else

{

if (arr[mid] == key)

return mid;

else if (arr[mid] > key)

{

return BinarySearch(arr, low, mid - 1, key);
}
else
{

return BinarySearch(arr, mid + 1, high, key);
}

}
}