20240604 Eunoiay's submission for CF1949I (Yawn-Sean#3188)

daily_problems/2024/06/0604/personal_submission/cf1949i_Eunoiay.cpp

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+#include <bits/stdc++.h>
+
+using namespace std;
+using i64 = long long;
+
+int main() {
+	ios::sync_with_stdio(false);
+	cin.tie(nullptr);
+
+	int n;
+	cin >> n;
+
+	vector<int> x(n), y(n), r(n);
+	for (int i = 0; i < n; ++i) {
+		cin >> x[i] >> y[i] >> r[i];
+	}
+
+	vector<vector<int>> adj(n);
+	for (int i = 0; i < n; ++i) {
+		for (int j = 0; j < i; ++j) {
+			i64 dx = x[i] - x[j];
+			i64 dy = y[i] - y[j];
+			i64 dis = r[i] + r[j];
+			if (dx * dx + dy * dy == dis * dis) {
+				adj[i].push_back(j);
+				adj[j].push_back(i);
+			}
+		}
+	}
+
+	vector<int> clr(n, -1);
+	bool flg = false;
+
+	for (int i = 0; i < n; ++i) {
+		if (~clr[i]) {
+			continue;
+		}
+		clr[i] = 0;
+
+		stack<int> stk;
+		int c[2] = {};
+
+		c[0] = 1;
+		stk.push(i);
+
+		bool f = true;
+		while (!stk.empty()) {
+			auto u = stk.top();
+			stk.pop();
+
+			for (auto v : adj[u]) {
+				if (clr[v] == -1) {
+					clr[v] = clr[u] ^ 1;
+					c[clr[v]] += 1;
+					stk.push(v);
+				} else if (clr[u] == clr[v]) {
+					f = false;
+				}
+			}
+		}
+		if (f && c[0] != c[1]) {
+			flg = true;
+			break;
+		}
+	}
+
+	cout << (flg ? "YES" : "NO") << "\n";
+
+	return 0;
+}