Cod sursa(job #2037244)

Utilizator clau_rClaudia clau_r Data 11 octombrie 2017 21:49:59
Problema Algoritmul lui Dijkstra Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 2.14 kb
#include <iostream>
#include <vector>
#include <list>
#include <queue>
#include <stdio.h>
#include <string.h>
#include <limits>

const int maxn = 50001;
const int inf = 1 << 30;

FILE *in = fopen("dijkstra.in","r"), *out = fopen("dijkstra.out","w");
using namespace std;

class Graph
{
public:
    std::list<std::pair<int, int> >* neigh;
    int n;
    
    Graph(int n) {
        this->n = n + 1;
        neigh = new std::list<std::pair<int, int>> [n + 1];
    }
    
    void addEdge(int u, int v, int w) {
        neigh[u].push_back(make_pair(v, w));
        neigh[v].push_back(make_pair(u, w));
    }
    
    void shortestPath(int source) {
        auto comparator = [](pair<int, int> p1, pair<int, int> p2) {
            return p1.second < p2.second;
        };
        
        priority_queue<pair<int, int>, vector<pair<int, int>>, decltype(comparator)> pq (comparator);
        vector<int> distance(n, INT_MAX -1);
        
        distance[source] = 0;
        pq.push(make_pair(source, 0));
        
        while(pq.size() != 0) {
            auto node = pq.top();
            pq.pop();
            //std::cout << "Value: " << node.first << " " << node.second << "\n";
            
            for (const auto& child : neigh[node.first]) {
                //std::cout << "Getting to child: " << child.first << " " << child.second << " " << distance[child.first] << "\n";
                if (distance[child.first] > distance[node.first] + child.second) {
                 distance[child.first] = distance[node.first] + child.second;
                 //std::cout << "Updating: " << child.first << " " << distance[child.first]<< "\n";
                 pq.push(make_pair(child.first, distance[child.first]));
             }
            }
        }
        
        for ( int i = 2; i < n; ++i)
            fprintf(out, "%d ", distance[i] == INT_MAX -1 ? 0 : distance[i]);
        fprintf(out, "\n");
        
    }
};

int main()
{
    int n, m;
    fscanf(in, "%d %d", &n, &m);
    Graph g(n);
    int x, y, z;
    for ( int i = 0; i < m; ++i )
    {
        fscanf(in, "%d %d %d", &x, &y, &z);
        g.addEdge(x, y, z);
    }
    
    g.shortestPath(1);
    
    return 0;
}