[검지offer] 정렬 수조에 나타나는 숫자를 통계합니다.

class Solution {
public:
    int GetNumberOfK(vector data ,int k) {
        int number = 0;
        if(data.size() == 0)
            return number;
        int first = GetFirstOfK(data,k,0,data.size()-1);
        int last = GetLastOfK(data,k,0,data.size() - 1);
        if(first > -1 && last >　-1)
            return last - first + 1;
        return number;
    }
    int GetFirstOfK(vector &data,int k,int low,int high){
        while(low <= high){
            int mid = (low + high) / 2;
            if(data[mid] == k){
                if(mid == 0 || (mid > 0 && data[mid-1] != k)){
                    return mid;
                }else{
                	high = mid - 1;
            	}
            }else if(data[mid] > k){
                high = mid - 1;
            }else{
                low = mid + 1;
            }
        }
        return -1;
    }
    int GetLastOfK(vector &data,int k,int low,int high){
        while(low <= high){
            int mid = (low + high) / 2;
            if(data[mid] == k){
                if( (mid == data.size() - 1) || ((mid < data.size() - 1) && data[mid+1] != k)){
                    return mid;
                }else{
                	low = mid + 1;
            	}
            }else if(data[mid] > k){
                high = mid - 1;
            }else{
                low = mid + 1;
            }
        }
        return -1;
    }
};