题解 | #数字在升序数组中出现的次数#

class Solution {
public:
    int GetNumberOfK(vector<int> data ,int k) {
        if(data.size() < 1)
            return 0;
        int l = 0, r = data.size() - 1;
        while(l < r) {
            int mid = (l + r) / 2;
            if(data[mid] < k)
                l = mid + 1;
            else
                r = mid;
        }
        int left = -1, right = -1;
        if(data[l] == k)
            left = l;
        l = 0, r = data.size() - 1;
        while(l < r) {
            int mid = (l + r + 1) / 2;
            if(data[mid] > k)
                r = mid - 1;
            else
                l = mid;
        }
        if(data[l] == k)
            right = l;
        if(left == -1)
            return 0;
        else
            return right - left + 1;
    }
};