二分查找法 C#实现
复习二分查找法。
public int FindPosition(int num, int[] arr)
{
int left = 0;
int right = arr.Length - 1;
while (left < right - 1)
{
if (arr[left] == num)
{
return left;
}
if (arr[right] == num)
{
return right;
}
int middle = (left + right) / 2;
if (num == arr[middle])
{
return middle;
}
else if (num < arr[middle])
{
right = middle;
}
else
{
left = middle;
}
}
return -1;
}