Cod sursa(job #2750195)

Utilizator andrei.florea0405Florea Andrei-Bogdan andrei.florea0405 Data 10 mai 2021 10:38:03
Problema Algoritmul lui Dijkstra Scor 20
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.89 kb
#include <bits/stdc++.h>
using namespace std;

const int kNmax = 100005;

class Task {
public:
    void solve() {
           read_input();
           print_output(get_result());
}

private:
    int n;
	int m;
	vector<pair<int, int>> adj[kNmax];
    int source;

	void read_input() {
		ifstream fin("dijkstra.in");
		fin >> n >> m;
		for (int i = 1, x, y, c; i <= m; i++) {
			fin >> x >> y >> c;
			adj[x].push_back(make_pair(y, c));
		}
        //fin >> source;
		fin.close();
	}


    vector<int> get_result() {
        vector<int> distances(n + 1, INT_MAX);  
        source = 1;  
        distances[source] = 0;

        priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
        // punand greater<pair..>, priority queue va fi ca un min heap
        // am pus costul si apoi nodul in pereche pentru ca, de exemplu (0, 100) < (1, 0)
        pq.push(make_pair(0, source));
        
        while (!pq.empty()) {
            pair<int, int> top = pq.top();
            pq.pop();

            int node = top.second;
            int cost = top.first;

            for (auto &neigh_pair : adj[node]) {
                int neigh = neigh_pair.first;
                int edgeCost = neigh_pair.second;

                if (distances[neigh] > cost + edgeCost) {
                    distances[neigh] = cost + edgeCost;
                    pq.push(make_pair(distances[neigh], neigh));
                }
            }
        }

        return distances;
    }
       

    void print_output(vector<int> distances) {
        ofstream fout("dijkstra.out");
        
        for (int i = 2; i <= n; i++) {
            int d = distances[i];

            if (d == INT_MAX) {
                fout << "-1 ";
            } else {
                fout << d << " ";
            }
        }
        
        fout.close();
    }
};


int main() {
    Task *task = new Task();
    task->solve();
    delete task;
    return 0;
}