排序后遍历加剪枝

#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <climits>
#include <set>
#include <map>

using namespace std;
using ll = long long;

struct Point {
    int x, y;
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

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

    // 按 x 排序
    sort(points.begin(), points.end(), [](const Point & a, const Point & b) {
        return a.x < b.x;
    });

    ll minDist = LLONG_MAX;

    // 使用滑动窗口
    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            // 如果 x 坐标差已经大于当前最小距离，可以提前跳出
            ll dx = points[i].x - points[j].x;
            if (dx * dx >= minDist) break;

            ll dy = points[i].y - points[j].y;
            ll dist = dx * dx + dy * dy;
            if (dist < minDist) {
                minDist = dist;
            }
        }
    }

    cout << minDist << endl;
    return 0;
}