Cod sursa(job #381349)

Utilizator pauldbPaul-Dan Baltescu pauldb Data 10 ianuarie 2010 13:53:42
Problema Ciclu hamiltonian de cost minim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.27 kb
#include <fstream>
#include <vector>
#include <cstring>

using namespace std;

const int MAXN = 20;
const int MAXX = 262150;
const int INF = 1000000000;

int N, M, Sol;
vector <int> A[MAXN];
int C[MAXX][MAXN];
int Cost[MAXN][MAXN];

int calc(int conf, int last)
{
	if (C[conf][last] == -1)
	{
		C[conf][last] = INF;

		for (size_t i = 0; i < A[last].size(); ++i) // parcurg nodurile care arata spre ultimul nod din lant 
			if (conf & (1 << A[last][i]))  // le aleg doar pe cele care apartin lantului
			{
				if (A[last][i] == 0 && conf != (1<<(last)) + 1) continue; // nodul 1 trebuie sa il scot ultimul

				C[conf][last] = min(C[conf][last], calc(conf ^ (1<<last), A[last][i]) + Cost[A[last][i]][last]); 
			}
	}

	return C[conf][last];
}

int main()
{
	ifstream fin("hamilton.in");
	ofstream fout("hamilton.out");

	Sol = INF;

	fin >> N >> M;

	for (int i = 0; i < N; ++i)
		for (int j = 0; j < N; ++j) Cost[i][j] = INF;

	for (int i = 1; i <= M; ++i)
	{
		int x, y;

		fin >> x >> y;
		A[y].push_back(x); // retin arcul invers
		fin >> Cost[x][y];
	}

	memset(C, -1, sizeof(C));
	C[1][0] = 0;

	for (size_t i = 0; i < A[0].size(); ++i)
		Sol = min(Sol, calc((1<<N)-1, A[0][i]) + Cost[A[0][i]][0]);

	if (Sol == INF) fout << "Nu exista solutie" << endl;
	else fout << Sol << endl;

	return 0;
}