Cod sursa(job #2865736)

Utilizator MihaiZ777MihaiZ MihaiZ777 Data 9 martie 2022 09:56:01
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.82 kb
#include <fstream>
#include <iostream>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;

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

const long long infinity = 2e12;

struct Edge
{
    int destination;
    int cost;

    inline bool operator < (const Edge& other) const
    {
        return cost > other.cost;
    }
};

int n, m;
vector <Edge> graph[50005];
priority_queue <Edge> heap;
long long distances[50005];
bool visited[50005];

void Dijkstra(int start)
{
    for (int i = 1; i <= n; i++)
    {
        distances[i] = infinity;
    }

    distances[1] = 0;
    Edge startingEdge = {start, 0};
    heap.push(startingEdge);

    while (!heap.empty())
    {
        Edge currEdge = heap.top();
        heap.pop();
        if (visited[currEdge.destination])
        {
            continue;
        }
        visited[currEdge.destination] = true;
        
        for (Edge edge : graph[currEdge.destination])
        {
            if (distances[edge.destination] <= edge.cost + distances[currEdge.destination])
            {
                continue;
            }
            distances[edge.destination] = edge.cost + distances[currEdge.destination];
            edge.cost = distances[edge.destination];
            heap.push(edge);
        }
    }
}

int main()
{
    ios::sync_with_stdio(false);
    fin >> n >> m;
    for (int i = 0; i < m; i++)
    {
        int a, b, c;
        fin >> a >> b >> c;
        Edge newEdge = {b, c};
        graph[a].push_back(newEdge);
    }

    Dijkstra(1);

    for (int i = 2; i <= n; i++)
    {
        if (distances[i] == infinity)
        {
            fout << 0 << ' ';
        }
        else
        {
            fout << distances[i] << ' ';
        }
    }
    fout << '\n';
}