Submission #826144

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Source Code Expand

#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <map>
#include <set>
#include <list>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <stack>
#include <iomanip>
#include <functional>

#define SIZE 300005
#define INF 1000000000
#define FD(d) fixed << setprecision(d)
#define MOD 1000000007
#define ll long long

using namespace std;

typedef pair<ll, ll> P;

int N, M;
int cnt = 0;
vector<int> B(10005);
bool l[10005];
vector<int> x(10005);
vector<int> y(10005);

void DFS(int m)
{
	if (m > M) {
		l[B[1]] = true;
		return;
	}
	for (int i = 1; i <= N; i++) {
		if (B[i] == x[m]) {
			B[i] = y[m];
			DFS(m + 1);
			B[i] = x[m];
		}
	}
}



int main()
{
	cin >> N >> M;
	
	for (int i = 1; i <= N; i++) {
		B[i] = i;
	}

	for (int i = 1; i <= N; i++) {
		cin >> x[i] >> y[i];
	}

	DFS(1);


	for (int i = 1; i <= N; i++) {
		if (l[i]) {
			cnt++;
		}
	}

	cout << cnt << endl;
	
	return(0);

}

Submission Info

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