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75 lines
1.4 KiB
C++
75 lines
1.4 KiB
C++
#include <iostream>
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#include <algorithm>
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#include <cmath>
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#include <iomanip>
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#include <queue>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 3005;
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const double eps = 1e-4;
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int n, row, line;
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std::pair<int, int> a[N];
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bool vis[N];
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bool check(double x) {
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std::fill_n(vis, N, false);
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std::queue<int> q;
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for (int i = 1; i <= n; i++) {
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if (a[i].first - 1 < x || line - a[i].second < x) {
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vis[i] = true;
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q.push(i);
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}
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}
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while (!q.empty()) {
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auto u = q.front();
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q.pop();
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if (row - a[u].first < x || a[u].second - 1 < x) {
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return false;
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}
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for (int i = 1; i <= n; i++) {
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if (!vis[i] && std::sqrt(std::pow(a[u].first - a[i].first, 2) + std::pow(a[u].second - a[i].second, 2)) < x * 2) {
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vis[i] = true;
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q.push(i);
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}
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}
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}
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return true;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n >> row >> line;
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for (int i = 1; i <= n; i++) {
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cin >> a[i].first >> a[i].second;
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}
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double l = 0, r = std::min(row, line);
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while (r - l > eps) {
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double mid = (l + r) / 2;
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if (check(mid)) {
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l = mid;
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} else {
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r = mid;
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}
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}
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cout << std::fixed << std::setprecision(2) << l << endl;
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return 0;
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}
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