Cod sursa(job #495487)

Utilizator feelshiftFeelshift feelshift Data 25 octombrie 2010 16:31:59
Problema Algoritmul lui Dijkstra Scor 20
Compilator cpp Status done
Runda Arhiva educationala Marime 1.64 kb
#include <fstream>
#include <vector>
#include <list>
using namespace std;

const int INFINITY = 1001;
int nodes,edges;
vector< list< pair<int,int> > > graph;
vector<int> father;
vector<int> dist;
vector<bool> visited;

void read();
void manageMemory();
void dijkstra(int startNode);
void write();

int main() {
	read();

	for(int i=1;i<=nodes;i++)
		if(!visited.at(i))
			dijkstra(i);

	write();

	return (0);
}

void read() {
	ifstream in("dijkstra.in");
	int from,to,cost;

	in >> nodes >> edges;
	manageMemory();

	for(int i=1;i<=edges;i++) {
		in >> from >> to >> cost;

		graph.at(from).push_back(make_pair(to,cost));
	}

	in.close();
}

void manageMemory() {
	graph.resize(nodes+1);
	father.resize(nodes+1);
	dist.resize(nodes+1);
	visited.resize(nodes+1);

	dist.assign(dist.size(),INFINITY);
	dist.at(1) = NULL;
}

void dijkstra(int startNode) {
	int toVisit = startNode;
	int count = NULL;
	pair<int,int> toVisitNext;
	
	while(count != nodes) {
		for(list< pair<int,int> >::iterator it=graph.at(toVisit).begin();it!=graph.at(toVisit).end();it++) {
			toVisitNext = make_pair(NULL,INFINITY);

			if(dist.at(toVisit) + it->second < dist.at(it->first))
				dist.at(it->first) = dist.at(toVisit) + it->second;

			if(it->second < toVisitNext.second)
				toVisitNext = make_pair(it->first,it->second);
		}

		if(!toVisitNext.first)
			break;
		else {
			toVisit = toVisitNext.first;
			count++;
		}
	}

}

void write() {
	ofstream out("dijkstra.out");

	for(int i=2;i<=nodes;i++)
		if(dist.at(i) != INFINITY)
			out << dist.at(i) << " ";
		else
			out << 0 << " ";

	out.close();
}