37、数字在排序数组中出现的次数

题目描述
统计一个数字在排序数组中出现的次数。

class Solution {
public:
    int GetNumberOfK(vector<int> data ,int k) {
        int n = data.size();
        int start = 0;
        int end = n-1;
        int mid;
        int count = 0;
        
        while(start<=end)
        {
            mid = (start + end)>>1;
            if(data[mid] == k)
                break;
            else if(data[mid] < k)
                start = mid + 1;
            else
                end = mid - 1;
        }
        if(start>end)
            return 0;
        int index1 = mid;
        while(index1>=0&&data[index1]==k)
        {
            count ++;
            index1 --;
        }
        int index2 = mid + 1;
        while(index2<n&&data[index2]==k)
        {
            count ++;
            index2 ++;
        }
        return count;
    }
};