Cod sursa(job #2126077)

Utilizator Horia14Horia Banciu Horia14 Data 9 februarie 2018 00:49:59
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.58 kb
#include<cstdio>
#include<vector>
#include<queue>
#define MAX_N 50000
#define oo 0x3f3f3f3f
using namespace std;

vector<pair<int,int>>g[MAX_N + 1];
queue<int>q;
int dist[MAX_N + 1], vizNode[MAX_N + 1], n, m;
bool used[MAX_N + 1], cycle;

void readGraph() {
    int x, y, cost;
    FILE *fin = fopen("bellmanford.in","r");
    fscanf(fin,"%d%d",&n,&m);
    for(int i = 0; i < m; i++) {
        fscanf(fin,"%d%d%d",&x,&y,&cost);
        g[x].push_back(make_pair(y,cost));
    }
    fclose(fin);
}

void BellmanFord(int source) {
    vector<pair<int,int>>::iterator it;
    int i, node;
    for(i = 1; i <= n; i++)
        dist[i] = oo;
    dist[source] = 0;
    q.push(source);
    used[source] = true;
    while(!q.empty() && !cycle) {
        node = q.front();
        q.pop();
        used[node] = false;
        for(it = g[node].begin(); it != g[node].end(); it++) {
            if(dist[(*it).first] > dist[node] + (*it).second) {
                dist[(*it).first] = dist[node] + (*it).second;
                if(!used[(*it).first]) {
                    q.push((*it).first);
                    used[(*it).first] = true;
                    if(++vizNode[(*it).first] > n)
                        cycle = true;
                }
            }
        }
    }
}

void printDistances() {
    FILE *fout = fopen("bellmanford.out","w");
    if(cycle)
        fprintf(fout,"Ciclu negativ!\n");
    else {
        for(int i = 2; i <= n; i++)
            fprintf(fout,"%d ",dist[i]);
        fprintf(fout,"\n");
    }
    fclose(fout);
}

int main() {
    readGraph();
    BellmanFord(1);
    printDistances();
    return 0;
}