class Solution {
public:
    int lower_bound(const vector<int > &nums, int target) {  // first elem >= target
        int l = 0;
        int r = nums.size();

        while (r - l > 1) {
            int mid = (l + r ) / 2;
            if (nums[mid] >= target) r = mid;
            else l = mid;
        }

        if (nums[l] >= target) return l;
        if (nums[r] >= target) return r;
        return -1;
    }
    int upper_bound(const vector<int > &nums, int target) { // first elem > target
        int l = 0;
        int r = nums.size();

        while (r - l > 1) {
            int mid = (l + r ) / 2;
            if (nums[mid] > target) r = mid;
            else l = mid;
        }

        if (nums[l] >= target) return l;
        if (nums[r] >= target) return r;
        return -1;
    }
    vector<int> searchRange(vector<int>& nums, int target) {
        int lb = lower_bound(nums, target);
        int ub = upper_bound(nums, target);

        if (lb == -1 || nums[lb] != target) return {-1, -1};
        if (ub == -1) {
            return {lb, (int)(nums.size() - 1) };
        } else {
            return {lb, ub};
        }
    }
};