Cod sursa(job #2058209)

Utilizator vasi461Vasiliu Dragos vasi461 Data 5 noiembrie 2017 12:02:52
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 2.08 kb
#include <fstream>
#include <vector>
using namespace std;

ifstream cin("dijkstra.in");
ofstream cout("dijkstra.out");

#define MAX 50005
#define INF 1000000005

int n, m, a, b, c, d[MAX], h[MAX], poz[MAX], k;
bool viz[MAX];
vector<pair<int, int> > g[MAX];

void up_heap(int x)
{
    while(x > 1 and d[h[x]] < d[h[x / 2]])
    {
        swap(h[x], h[x / 2]);
        swap(poz[h[x]], poz[h[x / 2]]);
        x /= 2;
    }
}

void down_heap(int x)
{
    int f;
    do
    {
        f = 0;
        if(2 * x <= k and d[h[x]] > d[h[2 * x]])
        {
            f = 2 * x;
        }
        if(2 * x + 1 <= k and d[h[x]] > d[h[2 * x + 1]] and d[h[2 * x + 1]] < d[h[2 * x]])
        {
            f = 2 * x + 1;
        }
        if(f != 0)
        {
            swap(h[x], h[f]);
            swap(poz[h[x]], poz[h[f]]);
            x = f;
        }
    }
    while(f != 0);
}

void inserare(int x)
{
    h[++k] = x;
    poz[x] = k;
    up_heap(k);
}

void stergere(int x)
{
    h[poz[x]] = h[k];
    poz[h[k]] = poz[x];
    k--;
    up_heap(poz[x]);
    down_heap(poz[x]);
}

void dijkstra()
{
    for(int i = 1; i <= n; ++i)
    {
        d[i] = INF;
    }
    d[1] = 0;
    for(int i = 1; i <= n; ++i)
    {
        inserare(i);
    }
    for(int i = 1; i <= n; ++i)
    {
        int nod = h[1];
        stergere(nod);
        for(int j = 0; j < g[nod].size(); ++j)
        {
            int v = g[nod][j].first;
            int cost = g[nod][j].second;
            if(d[nod] + cost < d[v])
            {
                d[v] = d[nod] + cost;
                up_heap(poz[v]);
            }
        }
    }
}

int main()
{
    cin.sync_with_stdio(false);
    cin >> n >> m;
    for(int i = 1; i <= m; ++i)
    {
        cin >> a >> b >> c;
        g[a].push_back(make_pair(b, c));
    }
    dijkstra();
    for(int i = 2; i <= n; ++i)
    {
        if(d[i] == INF)
        {
            cout << 0 << ' ';
        }
        else
        {
            cout << d[i] << ' ';
        }
    }
    cout << '\n';
    return 0;
}