Cod sursa(job #2175545)

Utilizator cristicretancristi cretan cristicretan Data 16 martie 2018 17:44:18
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 1.6 kb
/// dijkstra
#include <iostream>
#include <fstream>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <utility>
#include <vector>
#include <set>
#include <unordered_set>
#include <iterator>
#define INF 0x3f3f3f3f
#define NMax 100001
///#define f cin
///#define g cout
using namespace std;

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

int n, m, x, y, cost;
vector<pair<int, int> > G[NMax];
multiset<pair<int, int> > H;
int dist[NMax];

void dijkstra(vector<pair<int, int> > G[NMax], int k)
{
    dist[k] = 0; /// distanta de la nodul de plecare e 0
    H.insert(make_pair(0, k)); /// pun in multiset nodul de plecare
    while(!H.empty()) /// cat timp nu mai sunt noduri
    {
        int nod = (*H.begin()).second; /// iau nodul de plecare
        H.erase(H.begin()); /// il scot din multiset
        for(int i = 0; i < G[nod].size(); ++i) /// ii parcurg vecinii
            if(dist[G[nod][i].first] > dist[nod] + G[nod][i].second) /// verific daca exista un drum mai bun
            {
                dist[G[nod][i].first] = dist[nod] + G[nod][i].second; /// actualizez
                H.insert(make_pair(dist[G[nod][i].first], G[nod][i].first)); /// il bag in multiset
            }
    }
}

int main()
{
    f >> n >> m;
    for(int i = 1; i <= m; ++i)
    {
        f >> x >> y >> cost;
        G[x].push_back(make_pair(y, cost));
    }
    memset(dist, INF, sizeof(dist)); /// fac toate distantele infinit
    dijkstra(G, 1);
    for(int i = 2; i <= n; ++i)
        if(dist[i] == INF) g << 0 << " ";
        else g << dist[i] << " ";
    return 0;
}