Closest points

#include <bits/stdc++.h>
#include <climits>

using namespace std;

struct Point {
    long long x, y;
};

bool mysort(Point &a, Point &b) {
    if (a.x == b.x)
        return a.y <= b.y;
    else
        return a.x < b.x;
}

long long euclidean_distance(Point &a, Point &b) {
    return (a.x - b.x)*(a.x - b.x) + (a.y - b.y)*(a.y - b.y);
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n;
    cin >> n;

    vector<Point> v(n);

    for (int i = 0; i < n; ++i) {
        cin >> v[i].x >> v[i].y;
    }

    sort(v.begin(), v.end(), mysort);

    long long mindist = euclidean_distance(v[0], v[1]);

    for (int i = 1; i < n; ++i) {
        //cout << "for " << i << endl;
        int j = i - 1;
        /*cout << (j >= 0) << endl;
        cout << (v[j].x <= (v[i].x + mindist)) << endl;
        cout << (v[j].x >= (v[i].x - mindist)) << endl;
        cout << (v[j].y <= (v[i].y + mindist)) << endl;
        cout << (v[j].y >= (v[i].y - mindist)) << endl;*/
        while (j >= 0 
            and v[j].x <= (v[i].x+mindist) 
            and v[j].x >= (v[i].x-mindist) 
            and (v[j].y <= (v[i].y+mindist)) 
            and (v[j].y >= (v[i].y-mindist))
        ) {
            //cout << "cheking distance between " << v[j].x << " " << v[j].y << " " << v[i].x << " " << v[i].y << endl;
            long long ec = euclidean_distance(v[j], v[i]);
            if (ec < mindist) {
                mindist = ec;
                //cout << "mindist updated: " << mindist << endl;
            }
            --j;
        }
    }
    cout << mindist << 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