Cod sursa(job #782031)

Utilizator stefanzzzStefan Popa stefanzzz Data 25 august 2012 17:41:37
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.56 kb
#include <fstream>
#include <vector>
#define MAXN 1005
using namespace std;
ifstream f("maxflow.in");
ofstream g("maxflow.out");

int n,m,x,y,z,c[MAXN][MAXN],fx[MAXN][MAXN],back[MAXN],cnt,mn,maxflow;
vector<int> G[MAXN],q;
bool uz[MAXN];

bool BFS();

int main()
{
    int i;
    f>>n>>m;
    for(i=1;i<=m;i++){
        f>>x>>y>>z;
        G[x].push_back(y);
        G[y].push_back(x);
        c[x][y]=z;}
    uz[1]=1;
    back[1]=-1;
    while(BFS()){
        for(i=0;i<G[n].size();i++){
            x=G[n][i];
            if(fx[x][n]==c[x][n]||!uz[x])continue;
            mn=c[x][n]-fx[x][n];
            while(back[x]!=-1){
                y=x;
                x=back[x];
                if(c[x][y]-fx[x][y]<mn)
                    mn=c[x][y]-fx[x][y];}
            if(!mn)continue;
            x=G[n][i];
            fx[x][n]+=mn;
            while(back[x]!=-1){
                y=x;
                x=back[x];
                fx[x][y]+=mn;
                fx[y][x]-=mn;}}}
    for(i=0;i<G[1].size();i++)
        maxflow+=fx[1][G[1][i]];
    g<<maxflow<<'\n';
    f.close();
    g.close();
    return 0;
}

bool BFS(){
    int i;
    for(i=2;i<=n;i++)
        uz[i]=0;
    cnt=0;
    q.clear();
    q.push_back(1);
    while(cnt<q.size()){
        x=q[cnt++];
        if(x==n)
            continue;
        for(i=0;i<G[x].size();i++){
            if(!uz[G[x][i]]&&fx[x][G[x][i]]<c[x][G[x][i]]){
                q.push_back(G[x][i]);
                uz[G[x][i]]=1;
                back[G[x][i]]=x;}}}
    return uz[n];}