剑指offer38 数字在排序数组中出现的次数

这种方法没用迭代，而是使用了循环的方式

class Solution {
public:
    int GetNumberOfK(vector<int> data ,int k) {
        if(data.empty())
            return ;
        int First = getFirstofK(data,k);
        int Last = getLastofK(data,k);
        if(First == - || Last == -)
            return ;
        else
            return Last - First + ;
    }
    int getFirstofK(vector<int> data,int k){
        int length = data.size();
        int begin = ;
        int end = length - ;
        while(begin <= end){
            int mid = (begin + end)/;
            if(data[mid] == k){
                if(data[mid-] != k)
                    return mid;
                else
                    end = mid - ;
            }
            else if(data[mid] < k)
                begin = mid + ;
            else
                end = mid - ;
        }
        return -;
    }
    int getLastofK(vector<int> data,int k){
        int length = data.size();
        int begin = ;
        int end = length - ;
        while(begin <= end){
            int mid = (begin + end)/;
            if(data[mid] == k){
                if(data[mid+] != k)
                    return mid;
                else
                    begin = mid + ;
            }
            else if(data[mid] < k)
                begin = mid + ;
            else
                end = mid - ;
        }
        return -;
    }
};