题解 | #JZ72 数字在升序数组中出现的次数#

//二分查找
class Solution {
public:
    int GetNumberOfK(vector<int> data ,int k) {
        int leftBound, rightBound;
        
        //查找下界
        int left = 0, right = data.size();
        while (left < right) {
            int mid = (left + right) / 2;
            if (data[mid] < k) left = mid + 1;
            else right = mid;
        }
        leftBound = left;
        
        //查找上界
        left = 0, right = data.size();
        while (left < right) {
            int mid = (left + right) / 2;
            if (data[mid] <= k) left = mid + 1;
            else right = mid;
        }
        rightBound = right;
        
        return rightBound - leftBound;
    }
};