658. Find K Closest Elements

Given a sorted integer array arr, two integers k and x, return the k closest integers to x in the array. The result should also be sorted in ascending order.

An integer a is closer to x than an integer b if:

• |a - x| < |b - x|, or
• |a - x| == |b - x| and a < b

class Solution {
public:
    vector<int> findClosestElements(vector<int>& arr, int k, int x) {
        int r = lower_bound(begin(arr), end(arr), x) - begin(arr), l = r - 1;
        vector<int> res;
        while(k--) {
            if(l == -1) res.push_back(arr[r++]);
            else if(r == arr.size()) res.push_back(arr[l--]);
            else {
                if(abs(arr[r] - x) < abs(arr[l] - x)) res.push_back(arr[r++]);
                else res.push_back(arr[l--]);
            }
        }
        sort(begin(res), end(res));
        return res;
    }
};