Closest points

#include <bits/stdc++.h>

using namespace std;

long long distance(pair<long long, long long> p1, pair<long long, long long> p2) {
    return (p1.first - p2.first)*(p1.first - p2.first) + (p1.second - p2.second)*(p1.second - p2.second);
}

int main() {

    int n;
    cin >> n;

    vector<pair<long long, long long>> points(n);
    for (int i = 0; i < n; i++)
        cin >> points[i].first >> points[i].second;

    sort(points.begin(), points.end());

    long long d = distance(points[0], points[1]);

    for (int i = 1; i < n; i++) {

        int j = i-1;

        while (j >= 0
            && abs(points[j].first - points[i].first) <= d
            && abs(points[j].second - points[i].second) <= 2*d) {

            long long dist = distance(points[i], points[j]);
        
            if (dist < d) {
                d = dist;
            }

            j -= 1; 

        }

    }

    cout << d << endl;

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED