Cod sursa(job #2291482)

Utilizator Alex03Runcan Alexandru Alex03 Data 28 noiembrie 2018 07:32:55
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.02 kb
#include <bits/stdc++.h>
using namespace std;
const char iname[] = "bellmanford.in";
const char oname[] = "bellmanford.out";
const int MAX_N = 50005;
const int INF = 0x3f3f3f3f;
vector < pair <int, int> > adj[MAX_N];
vector <int> adj_t[MAX_N];

int main(void) {
     ifstream in(iname);
     int nodes, edges;
     assert(in >> nodes >> edges);
     assert(1 <= nodes && nodes <= 50000);
     assert(1 <= edges && edges <= 250000);
     for (int i = 0; i < edges; ++ i) {
         int x, y, c;
         assert(in >> x >> y >> c);
         assert(1 <= x && x <= nodes);
         assert(1 <= y && y <= nodes);
         assert(-1000 <= c && c <= 1000);
         adj[x].push_back(make_pair(y, c));
         assert(find(adj_t[x].begin(), adj_t[x].end(), y) == adj_t[x].end());
         adj_t[x].push_back(y);
     }
     in.close();
     queue <int> Q;
     bitset <MAX_N> in_queue(false);
     vector <int> dist(MAX_N, INF), cnt_in_queue(MAX_N, 0);
     int negative_cycle = false;
     dist[1] = 0, Q.push(1), in_queue[1].flip();
     while (!Q.empty() && !negative_cycle)  {
         int x = Q.front();
         Q.pop();
         in_queue[x] = false;
         vector < pair <int, int> >::iterator it;
         for (it = adj[x].begin(); it != adj[x].end(); ++ it) if (dist[x] < INF)
             if (dist[it->first] > dist[x] + it->second) {
                 dist[it->first] = dist[x] + it->second;
                 if (!in_queue[it->first]) {
                     if (cnt_in_queue[it->first] > nodes)
                         negative_cycle = true;
                     else {
                         Q.push(it->first);
                         in_queue[it->first] = true;
                         cnt_in_queue[it->first] ++;
                     }
                 }
             }
     }
     ofstream out(oname);
     if (!negative_cycle) {
         for (int i = 2; i <= nodes; ++ i)
             out << dist[i] << " ";
     }
     else
         out << "Ciclu negativ!\n";
     out.close();
     return 0;
 }