Cod sursa(job #2490923)

Utilizator 1chiriacOctavian Neculau 1chiriac Data 11 noiembrie 2019 13:00:15
Problema Algoritmul Bellman-Ford Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.88 kb
#include <cstdio>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
#define DIM 10000
char buff[DIM];
int poz=0;
 
void citeste(int &numar)
{
     numar = 0;
     //cat timp caracterul din buffer nu e cifra ignor      
     while (buff[poz] < '0' || buff[poz] > '9')     
          //daca am "golit" bufferul atunci il umplu
          if (++poz == DIM) 
               fread(buff,1,DIM,stdin),poz=0;
     //cat timp dau de o cifra recalculez numarul          
     while ('0'<=buff[poz] && buff[poz]<='9')
     {
          numar = numar*10 + buff[poz] - '0';
          if (++poz == DIM) 
               fread(buff,1,DIM,stdin),poz=0;               
     }     
}
int n,m,nod,lungime,vizitat[50003],grad[50003],cost[50003];bool ok;
vector < pair <int,int> > graf[50003];
queue < pair <int,int> > chestie;
void bellman_ford () {
	while(chestie.size()!=0) {
		nod=chestie.front().first;
		lungime=chestie.front().second;
		for(int i=0;i<(int)graf[nod].size();++i) 
			if(vizitat[graf[nod][i].first]<(n-1)*grad[graf[nod][i].first]) {
				++vizitat[graf[nod][i].first];
				if(cost[graf[nod][i].first]>cost[nod]+graf[nod][i].second)
					cost[graf[nod][i].first]=cost[nod]+graf[nod][i].second,chestie.push(make_pair(graf[nod][i].first,cost[graf[nod][i].first]));
			}
			else
				if(cost[graf[nod][i].first]>cost[nod]+graf[nod][i].second){
					printf("Ciclu negativ!");ok=false;
					return ;
				}
		chestie.pop();	
	}
}

int main () {
	int nr1,nr2,nr3;
	freopen("bellmanford.in","r",stdin);
	freopen("bellmanford.out","w",stdout);
	citeste(n);citeste(m);
	for(int i=1;i<=m;++i) {
		//scanf("%d%d%d", &nr1, &nr2, &nr3);
		citeste(nr1);citeste(nr2);citeste(nr3);
		graf[nr1].push_back(make_pair(nr2,nr3));
		grad[nr2]++;
	}
	for(int i=2;i<=n;++i)
		cost[i]=1e9;
	ok=true;
	chestie.push(make_pair(1,0));
	bellman_ford();
	if(ok==true)
		for(int i=2;i<=n;++i)
			printf("%d ", cost[i]);
	return 0;
}