Cod sursa(job #474399)

Utilizator mlazariLazari Mihai mlazari Data 3 august 2010 17:53:21
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.23 kb
#include<fstream>
#include<vector>
#include<queue>

using namespace std;

#define NMAX 1003

ifstream fi("maxflow.in");
ofstream fo("maxflow.out");

int n,m,x,y,fmin,flow,i,nod;
int cap[NMAX][NMAX],flux[NMAX][NMAX],t[NMAX];
bool viz[NMAX];
vector<int> v[NMAX];
queue<int> q;

bool bfs() {
  int i,nod;
  for(i=2;i<=n;++i) viz[i]=false;
  viz[1]=true;
  q.push(1);
  while(!q.empty()) {
    nod=q.front();
    q.pop();
    if(nod==n) continue;
    for(i=0;i<v[nod].size();++i) {
      if(viz[v[nod][i]] || flux[nod][v[nod][i]]==cap[nod][v[nod][i]]) continue;
      q.push(v[nod][i]);
      viz[v[nod][i]]=true;
      t[v[nod][i]]=nod;
    }
  }
  return viz[n];
}

int main() {
  fi>>n>>m;
  while(m--) {
    fi>>x>>y;
    fi>>cap[x][y];
    v[x].push_back(y);
    v[y].push_back(x);
  }
  while(bfs())
   for(i=0;i<v[n].size();++i) {
     if(flux[v[n][i]][n]==cap[v[n][i]][n]) continue;
     fmin=cap[v[n][i]][n]-flux[v[n][i]][n];
     for(nod=v[n][i];nod!=1;nod=t[nod])
      fmin=min(fmin,cap[t[nod]][nod]-flux[t[nod]][nod]);
     flow+=fmin;
     t[n]=v[n][i];
     for(nod=n;nod!=1;nod=t[nod]) {
       flux[t[nod]][nod]+=fmin;
       flux[nod][t[nod]]-=fmin;
     }
   }
  fo<<flow;
  return 0;
}