C# 改进版二分查找法

public static int BinarySearchRecursion(IList<int> arry, ref int value)
{
    //如果传入的数组为空或者数组长度<=0那么就返回-1。防御性编程
    if (arry == null || arry.Count <= 0)
        return -1;
    int start = 0;
    int end = arry.Count - 1;
    return BinarySearchRecursion(arry, ref value, ref start, ref end);
}

private static int BinarySearchRecursion(IList<int> arry, ref int value, ref int start, ref int end)
{
    if (start > end)
        return -1;

    int mid = start + (end - start) / 2;
    if (arry[mid] == value)
        return mid;

    else if (value < arry[mid])
    {
        end = mid - 1;
        return BinarySearchRecursion(arry, ref value, ref start, ref end);
    }
    else
    {
        start = mid + 1;
        return BinarySearchRecursion(arry, ref value, ref start, ref end);
    }
}

 测试代码

static void Main(string[] args)
{
    Stopwatch watchTemp = new Stopwatch();

    //int[] arry = new int[100000];
    IList<int> arry = new List<int>();
    for (int i = 0; i < 300; i++)
    {
        arry.Add(i);
    }
    int value = 100;

    watchTemp.Start();
    int index = BinarySearchRecursion(arry, ref value);
    watchTemp.Stop();
    Console.WriteLine(index.ToString() + "-二分时间:" + watchTemp.Elapsed.TotalSeconds.ToString("0.00000"));

    //watchTemp.Start();
    //int index2 = (from p in arry where p == value select p).Count();
    //watchTemp.Stop();
    //Console.WriteLine(index2.ToString() + "-Linq时间:" + watchTemp.Elapsed.TotalSeconds.ToString("0.00000"));
}

 

参考自：http://www.cnblogs.com/xwdreamer/archive/2012/05/07/2487246.html