Cod sursa(job #3203825)

Utilizator BledeaAlexBledea Alexandru BledeaAlex Data 14 februarie 2024 19:10:21
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.46 kb
///dijkstra2 pbinfo

#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <climits>

using namespace std;

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

const int N_MAX = 50001;
int n, m;

struct path{
    int nod, cost;
};

vector<int> costs;
vector<path> vecini[N_MAX];
vector<bool> inQueue;

struct QueueCmp{
    bool operator()(const int& x, const int& y){
        return costs[x] > costs[y];
    }
};

priority_queue<int, vector<int>, QueueCmp> Q;

void Dijkstra(int sursa){
    costs.resize(n + 1, INT_MAX);
    inQueue.resize(n + 1, false);

    costs[sursa] = 0;
    Q.push(sursa);
    inQueue[sursa] = false;

    while(not Q.empty()){
        int nod = Q.top();
        inQueue[nod] = false;

        for(const path& vecin : vecini[nod])
            if(costs[vecin.nod] > costs[nod] + vecin.cost){
                costs[vecin.nod] = costs[nod] + vecin.cost;

                if(not inQueue[vecin.nod]){
                    Q.push(vecin.nod);
                    inQueue[vecin.nod] = true;
                }
            }

        Q.pop();
    }
}

int main()
{
    f >> n >> m;

    for(int i = 0, n1, n2, c; i < m; ++i){
        f >> n1 >> n2 >> c;
        vecini[n1].push_back(path{n2, c});
    }

    Dijkstra(1);

    for(int i = 2; i <= n; ++i)
        if(costs[i] != INT_MAX)
            g << costs[i] << ' ';
        else
            g << 0 << ' ';

    return 0;
}