Cod sursa(job #3299469)

Utilizator Gabriel_DaescuDaescu Gabriel Florin Gabriel_Daescu Data 6 iunie 2025 21:00:16
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.08 kb
#include <fstream>
#include <vector>
#define NMAX 50002
#define INF (1<<30)
using namespace std;
ifstream  fin("dijkstra.in");
ofstream fout("dijkstra.out");
int N,M,H,heap[NMAX],poz[NMAX];
vector<int> cost(NMAX,INF);
vector<pair<int,int>> graph[NMAX];

void citire()
{
    int A,B,C;
    fin>>N>>M;

    for(int i=1; i<=M; i++)
    {
        fin>>A>>B>>C;
        graph[A].push_back({B,C});
    }
}

void urcare(int ind)
{
    while(ind/2>=1 && cost[heap[ind]]<cost[heap[ind/2]])
    {
        swap(poz[heap[ind]],poz[heap[ind/2]]);
        swap(heap[ind],heap[ind/2]);
        ind=ind/2;
    }
}

void coborare(int ind)
{
    while(2*ind<=H)
    {
        int r=2*ind;
        if(r+1<=H && cost[heap[r+1]]<cost[heap[r]])
        {
            r++;
        }

        if(cost[heap[r]]<cost[heap[ind]])
        {
            swap(poz[heap[ind]],poz[heap[r]]);
            swap(heap[ind],heap[r]);
            ind=r;
        }
        else
        {
            break;
        }
    }
}

void adaugare_heap(int nod)
{
    H++;
    heap[H]=nod;
    poz[nod]=H;
    urcare(H);
}

void eliminare_minim()
{
    poz[heap[H]]=1;
    poz[heap[1]]=0;
    swap(heap[1],heap[H]);
    H--;
    coborare(1);
}

int main()
{
    citire();

    H=0;
    cost[1]=0;
    adaugare_heap(1);

    while(H>0)
    {
        int nod=heap[1];
        eliminare_minim();

        for(int i=0; i<graph[nod].size(); i++)
        {
            int next_nod=graph[nod][i].first;
            if(cost[next_nod]>cost[nod]+graph[nod][i].second)
            {
                cost[next_nod]=cost[nod]+graph[nod][i].second;
                if(!poz[next_nod])
                {
                    adaugare_heap(next_nod);
                }
                else
                {
                    urcare(poz[next_nod]);
                }
            }
        }
    }

    for(int i=2; i<=N; i++)
    {
        if(cost[i]==INF)
        {
            cost[i]=0;
        }
        fout<< cost[i] << " ";
    }
    fout<< "\n";

    return 0;
}