Cod sursa(job #2641967)

Utilizator Marius7122FMI Ciltea Marian Marius7122 Data 13 august 2020 12:11:18
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.01 kb
// BELLMAN-FORD

#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <limits.h>

using namespace std;

ifstream fin("dijkstra.in");
ofstream fout("dijkstra.out");

const int INF = 1 << 30;

typedef pair<pair<int, int>, int> muchie;
 
int n, m;
 
vector<int> BellmanFordNeoptimizat(const vector<muchie> &muchii, int s)
{
    vector<int> dist(n + 1, INF);
    dist[s] = 0;

    bool optim;
    do
    {
        optim = true;

        for(muchie m : muchii)
        {
            int x = m.first.first;
            int y = m.first.second;
            int cost = m.second;
            if(dist[y] > dist[x] + cost)
            {
                dist[y] = dist[x] + cost;
                optim = false;
            }
        }
    } while(!optim);

    return dist;
}

vector<int> BellmanFordCoada(const vector<vector<pair<int, int>>> &g, int s)
{
    vector<int> dist(n + 1, INF);
    vector<bool> inCoada(n + 1);
    dist[s] = 0;

    queue<int> q;
    q.push(s);
    inCoada[s] = true;
    while(!q.empty())
    {
        int x = q.front();
        q.pop();
        inCoada[x] = false;

        for(auto neigh : g[x])
        {
            int y = neigh.first;
            int cost = neigh.second;

            if(dist[x] + cost < dist[y])
            {
                dist[y] = dist[x] + cost;
                if(!inCoada[y])
                {
                    q.push(y);
                    inCoada[y] = true;
                }
            }
        }
    }

    return dist;
}

int main()
{
	fin >> n >> m;
    vector<vector<pair<int, int>>> g;
    g.resize(n + 1);
    for(int i = 0; i < m; i++)
    {
        int x, y, cost;
        fin >> x >> y >> cost;
        g[x].push_back({y, cost});
    }

    vector<int> dist = BellmanFordCoada(g, 1);

    for(int i = 2; i <= n; i++)
        if(dist[i] != INF)
            fout << dist[i] << ' ' ;
        else 
            fout << "0 ";
    fout << '\n';

    return 0;
}