AC Code

cses1666.cpp

@@ -0,0 +1,47 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+#define int long long
+const int maxN = 1e5 + 5;
+
+vector<int>nodes[maxN];
+vector<int>result;
+vector<bool>vis(maxN, false);
+
+
+void dfs (int node)
+{
+	vis[node] = true;
+	for (auto v : nodes[node])
+	{
+		if (vis[v] == false)
+		{
+			dfs(v);
+		}
+	}
+}
+
+signed main()
+{
+	int n, m;
+	cin >> n >> m;
+	for (int i = 1; i <= m; i++)
+	{
+		int u, v;
+		cin >> u >> v;
+		nodes[u].push_back(v);
+		nodes[v].push_back(u);
+	}
+	for (int i = 1; i <= n; i++)
+	{
+		if (vis[i] == false)
+		{
+			result.push_back(i);
+			dfs(i);
+		}
+	}
+	cout << result.size() - 1 << endl;
+    for (int i = 0; i < result.size() - 1; i++) {
+      cout << result[i] << " " << result[i + 1] << endl;
+    }
+}