Cod sursa(job #2867191)

Utilizator SmauSmau George Robert Smau Data 10 martie 2022 11:29:02
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.05 kb
#include <bits/stdc++.h>
 
#define INF 0x3f3f3fLL
 
using namespace std;
 
ifstream fin("dijkstra.in");
ofstream fout("dijkstra.out");
 
struct Neighbour {
    int node, cost;
    friend bool operator > (const Neighbour & a, const Neighbour & b) {
        return a.cost > b.cost;
    }
};
 
vector <vector <Neighbour>> G;
vector <int> C;
 
int n, m;
 
void Dijkstra(int start) {
    vector <bool> used(n + 1, false);
    C = vector <int> (n + 1, INF);
 
    // priority_queue <Neighbour, vector <Neighbour>, greater <Neighbour>> pq;
    // pq.push({start, 0});
    // C[start] = 0;
 
    // while(!pq.empty()) {
    //     int Node = pq.top().node;
    //     pq.pop();

    //     if(used[Node]) continue;
    //     used[Node] = true;
 
    //     for(auto x : G[Node])
    //         if(C[x.node] > C[Node] + x.cost) {
    //             C[x.node] = C[Node] + x.cost;
    //             pq.push({x.node, C[x.node]});
    //         }
    // }

    class Compar {
        public:
            bool operator () (int a, int b) {
                return C[a] > C[b];
            }
    };

    priority_queue <int, vector <int>, Compar> H;
    H.push(start);
    C[start] = 0;

    for(int i = 1; i <= n; i ++) {
        int vfmin; 
        
        bool gasit = 0;
        while(!H.empty()) {
            vfmin = H.top(); H.pop();
            if(!used[vfmin]) {
                gasit = 1;
                break;
            }
        }

        if(gasit == 0) break;

        used[vfmin] = true;
        int min = C[vfmin];

        for(auto x : G[vfmin])
            if(!used[x.node] && C[x.node] > min + x.cost) {
                C[x.node] = min + x.cost;
                H.push(x.node);
            }
    }
}
 
int main() {
    fin >> n >> m;
    
    G.resize(n + 1);
 
    for(int i = 1; i <= m; i ++) {
        int x, y, c; fin >> x >> y >> c;
        G[x].push_back({y, c});
    }
 
    Dijkstra(1);
 
    for(int i = 2; i <= n; i ++)
        fout << (C[i] != INF ? C[i] : 0) << ' ';
    
    return 0;
}