Cod sursa(job #2375432)

Utilizator pistvanPeter Istvan pistvan Data 8 martie 2019 09:18:42
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.53 kb
#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
#include <climits>
#define MAXN 50001
#define INF INT_MAX
using namespace std;

int N, M;
vector<pair<int,int>> G[MAXN];
int dist[MAXN];
bool vis[MAXN];

void Read()
{
    ifstream g("dijkstra.in");
    g>>N>>M;
    int from, to, cost;
    for (int i=1;i<=M;i++)
    {
        g>>from>>to>>cost;
        G[from].push_back(make_pair(to, cost));
    }
    for (int i=1;i<=N;i++)
        dist[i]=INF;
}

void Dijkstra()
{
    int source, nextnode;
    priority_queue<pair<int,int>> pq;
    pq.push(make_pair(0, 1));
    dist[1]=0;
    while (!pq.empty())
    {
        source=pq.top().second;
        pq.pop();
        if (vis[source])
            continue;
        for (vector<pair<int,int>>::iterator it=G[source].begin();it!=G[source].end();++it)
        {
            nextnode=it->first;
            if (vis[nextnode])
                continue;
            if (dist[nextnode]>dist[source]+it->second)
            {
                dist[nextnode]=dist[source]+it->second;
                //cout<<"Optimized node "<<nextnode<<" from "<<source<<" to weight "<<dist[nextnode]<<'\n';
                pq.push(make_pair(-dist[nextnode], nextnode));
            }
        }
        vis[source]=1;
    }
}

void Write()
{
    ofstream g("dijkstra.out");
    for (int i=2;i<=N;i++)
    {
        if (dist[i]==INF)
            dist[i]=0;
        g<<dist[i]<<' ';
    }
}

int main()
{
    Read();
    Dijkstra();
    Write();
}