Cod sursa(job #1001756)

Utilizator manutrutaEmanuel Truta manutruta Data 25 septembrie 2013 23:04:25
Problema Algoritmul lui Dijkstra Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 2.22 kb
# include <cstring>
# include <iostream>
# include <fstream>
# include <vector>
# include <set>
using namespace std;

# define INF 0x3f3f3f3f
# define MAXN 50010
typedef vector< pair<int, int> > :: iterator iter;

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

class heap{
private:
    vector< pair<int, int> > a;
public:
    heap() {};

    # define father(x) (x >> 1)
    # define left_son(x) (x << 1)
    # define right_son(x) ((x << 1) + 1)

    void insert(pair<int, int> x) {
        a.push_back(x);
        int k = a.size() - 1;

        while ((k > 1) && (a[k] < a[father(k)])) {
            swap(a[k], a[father(k)]);
            k = father(k);
        }
    }

    pair<int, int> top() {
        return a[0];
    }

    void pop() {
        a[0] = a[a.size() - 1];
        a.pop_back();
        int k = 0;
        while (k < a.size() && (a[k] > a[left_son(k)] || a[k] > a[right_son(k)])) {
            if (a[left_son(k)] > a[right_son(k)]) {
                swap(a[k], a[right_son(k)]);
                k = right_son(k);
            } else {
                swap(a[k] , a[left_son(k)]);
                k = left_son(k);
            }
        }
    }

    bool empty() {
        return a.empty();
    }
};

int n, m;
vector<pair<int, int> > G[MAXN];
int dist[MAXN];
heap coada;

void dijkstra()
{
    memset(dist, 0x3f, sizeof(dist));
    dist[1] = 0;
    coada.insert(make_pair(0, 1));

    while (!coada.empty()) {
        pair<int, int> nd = coada.top();
        coada.pop();

        for (iter it = G[nd.second].begin(); it != G[nd.second].end(); it++) {
            if (dist[it->first] > dist[nd.second] + it->second) {
                dist[it->first] = dist[nd.second] + it->second;
                coada.insert(make_pair(dist[it->first], it->first));
            }
        }
    }

    for (int i = 2; i <= n; i++) {
        if (dist[i] == INF) {
            g << 0 << ' ';
        } else {
            g << dist[i] << ' ';
        }
    }
}

int main()
{
    f >> n >> m;
    for (int i = 1; i <= m; i++) {
        int x, y, cost;
        f >> x >> y >> cost;
        G[x].push_back(make_pair(y, cost));
    }

    dijkstra();

    return 0;
}