昨天面试有一个二分查找的题目，题目大致是有随机生成100个整数，用二分查找法找出一个数字在这个100个数中的位置。当时二选一没有选择这道题目，今天早上起床做了一遍，以下是大致代码：
protected void Page_Load(object sender, EventArgs e)
{
int[] thisdata = data();
foreach(int a in thisdata)
{
Response.Write(a + " ");
}
Response.Write("<br/>");
thisdata = sorted(thisdata);
foreach (int a in thisdata)
{
Response.Write(a + " ");
}
Response.Write("<br/>");
int result = BinarySearch(thisdata, 0, thisdata.Length - 1, 10);
Response.Write(result);
}
/// <summary>
/// 10个随机数组生成
/// </summary>
/// <returns></returns>
private int[] data()
{
Random rd = new Random();
int[] result = new int[10];
for (int i = 0; i < result.Length; i++)
{
result[i] = rd.Next(15);
}
return result;
}
/// <summary>
/// 对数组data进行由小到大排序
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
private int[] sorted(int[] data)
{
int temp=0;
for (int i = 0; i < data.Length; i++)
{
for (int j = i + 1; j < data.Length; j++)
{
if (data[j] < data[i])
{
temp = data[i];
data[i] = data[j];
data[j] = temp;
}
}
}
return data;
}
/// <summary>
/// 二分查找
/// </summary>
/// <param name="data"></param>
/// <param name="start"></param>
/// <param name="end"></param>
/// <param name="key"></param>
/// <returns></returns>
private int BinarySearch(int[] data, int start, int end, int key)
{
int result = -1;
if (start >= end && data[end] == key)
{
result = end;
}
else if (start == end && data[end] != key)
{
return result;
}
else
{
int newend = (start + end) / 2;
if (data[newend] == key)
result = newend;
else
result = ((key < data[newend]) ? BinarySearch(data, start, newend - 1, key) : BinarySearch(data, newend + 1, end, key));
}
return result;
}
