Cod sursa(job #2141686)

Utilizator jeanFMI - Petcu Ion Cristian jean Data 24 februarie 2018 15:38:03
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 1.89 kb
#include<iostream>
#include<algorithm>
#include<vector>
#include<unordered_map>
#include<queue>
#define INF (1<<30)
using namespace std;

typedef vector< vector<pair<int, int> > > Graph;

// map<int, int> dijkstra(Graph &G, int start) {
//     int N = G.size();
//     map<int, int> dist;
//     priority_queue<pair<int, int>, vector<pair<int, int> >, greater<pair<int, int > > > heap;

//     heap.push(make_pair(0, start));
//     while (dist.size() < N) {
//         pair<int, int> node = heap.top();
//         int d = node.first;
//         heap.pop();
//         dist[node.second] = d;
        
//         for (auto &it : G[node.second]) {
//             heap.push(make_pair(d + it.second, it.first));
//         }
//     }

//     return dist;
// }

vector<int> dist;

struct cmp {
    bool operator () (const int &i, const int &j) {
        return dist[i] > dist[j];
    } 
};

void dijkstra(Graph &G, int start) {
    priority_queue<int, vector<int>, cmp> heap;
    vector<bool> used(dist.size(), false);
    dist[start] = 0;
    
    heap.push(start);
    while (!heap.empty()) {
        int node = heap.top();
        heap.pop();
        
        if (!used[node]) {
            used[node] = true;
            for (auto &it : G[node]) {
                if (dist[it.first] > dist[node] + it.second) {
                    dist[it.first] = dist[node] + it.second;
                    heap.push(it.first);
                    used[node] = false;
                }
            }  
        }
    }
}

int main() {
    freopen("dijkstra.in", "r", stdin);
    freopen("dijkstra.out", "w", stdout);

    int N, M, x, y, c, i;
    cin >> N >> M;
    
    Graph G(N + 1);
    for (i = 0; i < M; i++) {
        cin >> x >> y >> c;
        G[x].push_back(make_pair(y, c));
    }

    dist.resize(N + 1, INF);
    dijkstra(G, 1);

    for (i = 2; i <= N; i++) {
        cout << ((dist[i] == INF) ? 0 : dist[i]) << ' ';
    }

    return 0;
}