二分查找

有序数组，查找某个数据，二分法，时间复杂度O(log2n)

int binary_sort(int arr[], int lenght, int value)
{
    if (arr == NULL || lenght == 0)
    {
        return -1;
    }
    int start =0;
    int end = lenght -1;
    while(start <= end)
    {
        int mid = start + ((end - start)>>1);
        if (value == arr[mid])
        {
            return mid;
        }
        else if(value > arr[mid])
        {
            start = mid + 1;
        }
        else
        {
            end = mid - 1;
        }
    }
}