From 96254947699986c59f0dc63d69fd4b76bd3ed43e Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Mon, 6 Jul 2026 19:08:08 +0200
Subject: Initial commit

---
 04_graph_algorithms/building_teams_1668.cpp | 37 +++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 04_graph_algorithms/building_teams_1668.cpp

(limited to '04_graph_algorithms/building_teams_1668.cpp')

diff --git a/04_graph_algorithms/building_teams_1668.cpp b/04_graph_algorithms/building_teams_1668.cpp
new file mode 100644
index 0000000..c98e14d
--- /dev/null
+++ b/04_graph_algorithms/building_teams_1668.cpp
@@ -0,0 +1,37 @@
+#include <iostream>
+#include <vector>
+
+bool visit(size_t i, int c, const std::vector<std::vector<size_t>>& a,
+    std::vector<int>& t) {
+	if (t[i] != 0) return true;
+	t[i] = c;
+	for (auto j : a[i])
+		if (t[j] == c)
+			return false;
+		else if (!visit(j, 3-c, a, t)) return false;
+	return true;
+}
+
+int main() {
+	size_t n, m;
+	std::cin >> n >> m;
+	std::vector<std::vector<size_t>> a(n);
+	for (size_t i = 0; i < m; i++) {
+		size_t x, y;
+		std::cin >> x >> y;
+		a[x-1].push_back(y-1);
+		a[y-1].push_back(x-1);
+	}
+
+	std::vector<int> t(n);
+	for (size_t i = 0; i < n; i++) {
+		if (t[i] == 0) {
+			if (!visit(i, 1, a, t)) {
+				std::cout << "IMPOSSIBLE\n";
+				return 0;
+			}
+		}
+	}
+	for (auto x : t) std::cout << x << " ";
+	std::cout << "\n";
+}
-- 
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