Cod sursa(job #2924089)

Utilizator raulboancaBoanca Raul Alin raulboanca Data 25 septembrie 2022 10:30:02
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.57 kb
#include <bits/stdc++.h>
using namespace std;

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

set < pair < int , int > > st;
int n,m;
vector < pair < int , int > > v[50005];
int dist[50005];
int x,y,c;

void citire() {
    f >> n >> m;
    for (int i=1;i<=m;i++) {
        f >> x >> y >> c;
        v[x].push_back({y,c});
    }
}

void init() {
    for (int i=1;i<=n;i++) {
        dist[i] = INT_MAX; ///pp ca nu exista nicio distanta => toate vor fi infinit
    }
    dist[1]=0; ///distanta de la 1 la 1 e 0
    st.insert({0,1}); ///o bagam in set => st.insert({distanta,nod});
}

void dijkstra() {
    while (st.empty()==0) {
        int nod = st.begin()->second; ///luam nodul care va fi cu distanta tinuta minte minima
        st.erase(st.begin()); ///il stergem pt ca l-am vizitat
        for (auto k:v[nod]) { ///parcurgem muchiile
            if (dist[k.first] > dist[nod] + k.second) { ///ver daca am gasit o distanta mai mica
                st.erase({dist[k.first],k.first}); ///stergem nodul cu distanta veche daca era cumva in set
                dist[k.first] = dist[nod] + k.second; ///initializam noua distanta minima gasita
                st.insert({dist[k.first],k.first}); ///bagam nodul cu distanta respectiva in set
            }
        }
    }
}

void afisare() {
    for (int i=2;i<=n;i++) {
        if (dist[i]==INT_MAX) {
            g << 0 << " ";
        }
        else {
            g << dist[i] << " ";
        }
    }
}

int main()
{
    citire();
    init();
    dijkstra();
    afisare();
    return 0;
}