Cod sursa(job #488390)

Utilizator gabipurcaruGabi Purcaru gabipurcaru Data 28 septembrie 2010 16:46:07
Problema Algoritmul lui Dijkstra Scor 80
Compilator cpp Status done
Runda Arhiva educationala Marime 1.26 kb
// infoarena: problema/dijkstra //

#include <fstream>
#include <queue>
#include <vector>

#define MAXN 50010
#define MAXM 250010
#define INF (unsigned long)1<<31
using namespace std;

ifstream in("dijkstra.in");
ofstream out("dijkstra.out");

unsigned long n,m,i,j,a,b,c,len[MAXM],fin[MAXM],dist[MAXN],next;
struct cmp
{
	inline bool operator() (unsigned long a, unsigned long b) const
	{
		return dist[a] >= dist[b];
	}
};
vector<unsigned long> g[MAXN];
vector<unsigned long>::iterator it;
priority_queue<unsigned long, vector<unsigned long>, cmp > q;
bool viz[MAXN];

int main()
{
	in>>n>>m;

	for(i=1; i<=m; i++)
	{
		in>>a>>b>>c;
		g[a].push_back(i);
		len[i]=c;
		fin[i]=b;
	}		
	viz[1]=true;
	for(i=2; i<=n; i++)
		dist[i] = INF;
	
	for(it=g[1].begin(); it!=g[1].end(); it++)
		dist[fin[*it]] = len[*it], q.push(fin[*it]);
		
	while(!q.empty())
	{
		do
			{next = q.top(); q.pop();}
		while(!q.empty() && viz[next]);
		
		if(viz[next])
			break;
		
		for(it=g[next].begin(); it!=g[next].end(); it++)
			if(!viz[fin[*it]] && dist[fin[*it]] > dist[next]+len[*it])
				dist[fin[*it]] = dist[next]+len[*it], q.push(fin[*it]);
			
		viz[next]=true;
	}
	for(i=2; i<=n; i++)
		out<<(dist[i]!=INF ? dist[i] : 0)<<' ';

	return 0;
}