Cod sursa(job #869790)

Utilizator SchumiDumitru Andrei Georgian Schumi Data 2 februarie 2013 12:15:51
Problema Algoritmul lui Dijkstra Scor 10
Compilator cpp Status done
Runda Arhiva educationala Marime 1.27 kb
#include <algorithm>
#include <fstream>
#include <queue>
#include <vector>

using namespace std;

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

#define FORIT(it, v) for (typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)

const int N = 50005;

int n, m;
int cost[N];
vector <pair <int, int> > graph[N];

struct cmp {
    bool operator() (pair <int, int> &a, pair <int, int> &b) {
        return a.second > b.second;
    }
};

priority_queue <pair <int, int>, vector <pair <int, int> >, cmp> heap;

void dijkstra(int start) {
    for (int i = 0; i <= n; ++i)
        cost[i] = 0x3f3f3f3f;

    cost[start] = 0;
    heap.push(make_pair(start, 0));

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

        FORIT(it, graph[top.first]) {
            int cost_curent = cost[top.first] + it->second;

            if (cost_curent < cost[it->first]) {
                cost[it->first] = cost_curent;
                heap.push(make_pair(it->first, cost[it->first]));
            }
        }
    }
}

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

    for (int i = 1; i <= m; ++i) {
        int a, b, c;
        f >> a >> b >> c;
        graph[a].push_back(make_pair(b, c));
    }

    dijkstra(1);

    for (int i = 2; i <= n; ++i)
        g << cost[i] << ' ';
}