Cod sursa(job #2791263)

Utilizator sorana5Gligor Sorana sorana5 Data 30 octombrie 2021 12:01:28
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.29 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <climits>

using namespace std;

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

vector < pair < int, int > > v[50002];
vector < pair < int, int > > q;
bool visited[50002];
int n, m, d[50002];

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

priority_queue < pair < int, int >, vector < pair <int, int > >, comp > pq;

/*int insert_element (pair <int, int> x)
{
    q.push_back(x);
}

int get_next_element ()
{
    int minim = q[0].second;
    int min_index = 0;

    for (int i = 0; i < q.size(); ++i)
    {
        if (q[i].second < minim)
        {
            minim = q[i].second;
            min_index = i;
        }
    }
    return min_index;
}

void delete_element (int index)
{
    q.erase(q.begin() + index);
}

bool is_structure_empty ()
{
    return q.size() == 0;
}*/

void dijkstra ()
{
    d[1] = 0;
    //insert_element({1, 0});
    pq.push({1, 0});
    //while (!is_structure_empty())
    while (!pq.empty())
    {
        //int curr_index = get_next_element();
        //pair < int, int > curr = q[curr_index];
        //cout << curr.first << " " << curr.second << '\n';
        //delete_element(curr_index);
        pair <int, int> curr = pq.top();
        pq.pop();
        if (!visited[curr.first])
        {
            visited[curr.first] = 1;
            for (auto it: v[curr.first])
            {
                if (!visited[it.first] && d[it.first] > d[curr.first] + it.second) ///dp[i] = min (dp[tata] + 1, dp[i])
                {
                    d[it.first] = d[curr.first] + it.second;
                    //insert_element({it.first, d[it.first]});
                    pq.push({it.first, d[it.first]});
                }
            }
        }
    }
}

int main()
{
    f>>n>>m;
    for (int i = 0; i < m; ++i)
    {
        int x, y, cost;
        f>>x>>y>>cost;
        v[x].push_back({y, cost});
    }
    for (int i = 2; i <= n; ++i)
        d[i] = INT_MAX;
    dijkstra();
    for (int i = 2; i <= n; ++ i)
        if (d[i] == INT_MAX)
            g<<"0 ";
        else
            g<<d[i]<<' ';
    g<<'\n';
    return 0;
}