Closest points

input/code.cpp: In function 'll minD(std::vector<std::pair<long long int, long long int> >)':
input/code.cpp:23:14: warning: variable 'it' set but not used [-Wunused-but-set-variable]
   23 |         auto it = activePs.begin();
      |              ^~

#include<bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair<ll,ll> P;
 
 
ll dist(P P1, P P2) {
    return (P2.first - P1.first) * (P2.first - P1.first) + (P2.second - P1.second) * (P2.second - P1.second);
}
 
ll minD(vector<P> Ps){
    ll minS = LLONG_MAX;
    ll n = Ps.size();
 
    sort(Ps.begin(), Ps.end());
 
    set<P> activePs = {{Ps[0].second, Ps[0].first}};
 
    ll j = 0;
    for (ll i = 1; i < n; i++) {
        auto it = activePs.begin();
 
        ll dd = ceil(sqrt(minS));
 
        while (j < i && Ps[j].first < Ps[i].first - dd) {
            activePs.erase({Ps[j].second, Ps[j].first});
            j++;
        }
 
        auto lowerBound = activePs.lower_bound({Ps[i].second - dd, 0});
        auto upperBound = activePs.upper_bound({Ps[i].second + dd, 0});
 
        for (auto it = lowerBound; it != upperBound; it++) {
            minS = min(minS, dist({it->second, it->first}, Ps[i]));
        } 
        activePs.insert({Ps[i].second, Ps[i].first});
    }
 
    return minS;
}
 
int main(){
    ll n;
    cin >> n;
    vector<P> vec(n);
 
    for(int i=0; i<n; i++){
        ll a,b;
        cin >> a >> b;
        vec[i]=make_pair(a,b);
    }
 
    
    cout << minD(vec) << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

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: ACCEPTED

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