Cod sursa(job #2801977)

Utilizator MateiDorian123Nastase Matei MateiDorian123 Data 17 noiembrie 2021 11:49:50
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.54 kb
#include <bits/stdc++.h>

using namespace std;
ifstream fin("dijkstra.in");
ofstream fout("dijkstra.out");

void dijkstra(vector<vector<pair<int, int>>> &ad, int n, int s){
    /// method to find Dijkstra's shortest path using
    /// in the priority queue we store elements of pair
    /// first -> cost from the start node to the current node
    /// second -> node

    const int INF = 0x3f3f3f3f;
    priority_queue< pair<int, int>, vector <pair<int, int> > , greater<pair<int, int> > > pq;
    vector<int> dist(n + 1, INF);


    pq.push(make_pair(0, s));  /// the cost to reach start node is always 0
    dist[s] = 0;

    while (!pq.empty()){
        int node = pq.top().second;  /// node is the current node
        pq.pop();

        for(pair<int,int> v : ad[node])                             ///  iterate through all vertexes reachable from node
            if (dist[v.first] > dist[node] + v.second){   ///  if there is shorted path to v through node
                dist[v.first] = dist[node] + v.second;    ///  update distance
                pq.push(make_pair(dist[v.first], v.first));
            }
    }

    for(int i = 2; i <= n; i++)
        if(dist[i] == INF) fout << 0 << " ";
        else fout << dist[i] << " ";
    fout.close();

}

int main() {

    int n, m, x, y, cost;
    fin >> n >> m;

    vector<vector<pair<int, int>>> ad(n + 1);

    for (int i = 1; i <= m; ++i) {
        fin >> x >> y >> cost;
        ad[x].push_back({y, cost});
    }


    dijkstra(ad, n, 1);

    return 0;
}