Find K Closest Elements

#pragma GCC optimize("Ofast")
static auto _ = [] () {ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

class Solution {
public:
    vector<int> findClosestElements(vector<int>& arr, int k, int x) {
        int r = lower_bound(arr.begin(), arr.end(), x) - arr.begin();
        int l = r - 1, idx = 0;
        vector < int > res(k);
        while(k--){
            if(l < 0) res[idx++] = arr[r++];
            else if(r >= arr.size()) res[idx++] = arr[l--];
            else if(abs(arr[l] - x) <= abs(arr[r] - x)) res[idx++] = arr[l--];
            else res[idx++] = arr[r++];
        }
        sort(res.begin(), res.end());
        return res;
    }
};