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() == 0) return 0;
        int l = 0, r = data.size() - 1, mid = 0;
        int left = 0, right = 0;
        while (l < r) {
            mid = l + r >> 1;
            if (data[mid] < k) {
                l = mid + 1;
            } else {
                r = mid;
            }
        }
        if (data[l] != k) return 0;
        left = l;
        l = 0, r = data.size() - 1;
        while (l < r) {
            mid = l + r + 1 >> 1;
            if (data[mid] <= k) {
                l = mid;
            } else {
                r = mid - 1;
            }
        }
        return l - left + 1;
    }
};