数字在排序数组中出现的次数

class Solution {
public:
    int GetNumberOfK(vector<int> data ,int k) {
        if(data.size()==0)
            return 0;
        
        int first = GetFirstK(data,k,0,data.size()-1);
        int last = GetLastK(data,k,0,data.size()-1);
        
        int number = 0;
        if (first > -1 && last > -1)
        {
            number = last - first + 1;
        }
       return number;
    }
    
    int GetFirstK(vector<int>& data, int k, int start, int end)
    {
        if (start > end)
        {
            return -1;
        }

        int middIndex = (start + end) / 2;
        int middData = data[middIndex];

        if (middData == k)
        {
            if ((middIndex > 0 && data[middIndex - 1] != k) || middIndex == 0)
            {
                return middIndex;
            }
            else
            {
                end = middIndex - 1;
            }
        }
        else if (middData > k)
        {
            end = middIndex - 1;
        }
        else
        {
            start = middIndex + 1;
        }

        return GetFirstK(data, k, start, end);
    }
    
    int GetLastK(vector<int> & data, int k, int start, int end)
    {
        if (start > end)
        {
            return -1;
        }

        int middIndex = (start + end) / 2;
        int middData = data[middIndex];

        if (middData == k)
        {
            if ((middIndex < data.size() - 1 && data[middIndex + 1] != k) || middIndex == end)
            {
                return middIndex;
            }
            else
            {
                start = middIndex + 1;
            }
        }
        else if (middData > k)
        {
            end = middIndex - 1;
        }
        else
        {
            start = middIndex + 1;
        }

        return GetLastK(data, k, start, end);
    }
};