test

+#include<iostream>
+
+using namespace std;
+
+int result;
+int N, M;
+bool areFriends[10][10];
+bool havePair[10];
+
+void counting(int n)
+{
+	bool finished = true;
+	int first = -1;
+	for (int i = 0;i < N;i++)
+	{
+		if (!havePair[i])
+		{
+			finished = false;
+			first = i;
+			break;
+		}
+	}
+
+	if (finished)
+	{
+		result += 1;
+		return;
+	}
+
+	for (int j = first + 1;j < N;j++)
+	{
+		if (!havePair[first] && !havePair[j] && areFriends[first][j])
+		{
+			havePair[first] = true;
+			havePair[j] = true;
+			counting(n+1);
+			havePair[first] = false;
+			havePair[j] = false;
+		}
+	}
+
+	return;
+}
+
+int main()
+{
+	int test;
+	cin >> test;
+
+	for (int t = 1;t <= test;t++)
+	{
+		result = 0;
+		for (int i = 0;i < 10;i++)
+		{
+			havePair[i] = false;
+			for (int j = 0;j < 10;j++)
+			{
+				areFriends[i][j] = false;
+			}
+		}
+
+		cin >> N >> M;
+
+		for (int i = 0;i < M;i++)
+		{
+			int a, b;
+			cin >> a >> b;
+			areFriends[a][b] = true;
+			areFriends[b][a] = true;
+		}
+
+		counting(0);
+
+		cout << result << endl;
+	}
+
+	return 0;
+}
\ No newline at end of file