# 【題解】CSES 2194 Minimum Euclidean Distance

```#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
using namespace std;

int n;
struct Point{
int x, y;
bool operator < (const Point &b) const{
if (x != b.x) return x < b.x;
return y < b.y;
}
};
vector <Point> v;
set <Point> st;

bool cmp(Point x, Point y){
if (x.y != y.y) return x.y < y.y;
return x.x < y.x;
}
long long sqr(long long x){
return x*x;
}
long long dis(Point a, Point b){
return sqr(a.x-b.x) + sqr(a.y-b.y);
}

int main() {
cin >> n;
for (int i = 0, x, y; i < n; i++){
cin >> x >> y;
v.push_back({x, y});
}
sort(v.begin(), v.end(), cmp);
int p = 0;
st.insert(v[0]);
st.insert(v[1]);
long long d = dis(v[0], v[1]);
for (int i = 2; i < n; i++){
while (p < i && sqr(v[i].y-v[p].y) > d){
st.erase(v[p]);
p++;
}
set<Point>::iterator it = st.lower_bound(v[i]);
set<Point>::iterator tmp = it;
for (int j = 0; j < 5; j++, tmp++){
if (tmp == st.end()) break;
d = min(d, dis(v[i], *tmp));
}
tmp = it;
for (int j = 0; j < 5; j++){
if (tmp == st.begin()) break;
tmp--;
d = min(d, dis(v[i], *tmp));
}
st.insert(v[i]);
}
cout << d << "\n";
}
```