数字在升序数组中出现的次数(upper_bound & lower_bound)

/*

返回迭代器 对应数组下标要-vt.begin()
upper_bound(vt.begin(),vt.end(), value)返回第一个大于查找数字下标

lower_bound()返回第一个大于等于查找数的下标


*/

int GetNumberOfK(vector<int> nums ,int target) {
        return upper_bound(nums.begin(), nums.end(), target) - lower_bound(nums.begin(), nums.end(), target);
}

class Solution {
public:
    int GetNumberOfK(vector<int> nums ,int target) {
        int lbound = 0, rbound = 0;
        //  lower_bound()
        int low = 0, high = nums.size();
        while (low < high) {
            int mid = low + (high - low) / 2;
            nums[mid] < target? low = mid + 1:high = mid;
        }
        lbound = low;
        //  upper_bound() 返回第一个大于查找数字下标         
            low = 0, high = nums.size();
        while (low < high) {
           int mid = low + (high - low) / 2;
           nums[mid] <= target? low = mid + 1: high = mid;
        }
        rbound = low;
        return rbound - lbound;
    }
};