Cod sursa(job #3328595)

Utilizator anca04Bizon Anca anca04 Data 9 decembrie 2025 13:13:26
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.7 kb
#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>
/// Edmonds-Karp
using namespace std;
ifstream f("maxflow.in");
ofstream g("maxflow.out");
const int NMAX = 1e3;
int capacitate[NMAX+1][NMAX+1];
int flux[NMAX+1][NMAX+1];
vector<int> G[NMAX+1];
int vis[NMAX+1],p[NMAX+1];
int n,m;

int bfs(int s,int d)
{
    for(int i=1;i<=n;i++)
    {
        vis[i]=0;
        p[i]=0;
    }
    queue<int> q;
    q.push(s);
    vis[s]=1;
    while(!q.empty())
    {
        int nod=q.front();
        q.pop();
        for(auto vecin:G[nod])
        {
            if(!vis[vecin] && capacitate[nod][vecin] - flux[nod][vecin]>0)
            {
                vis[vecin]=1;
                p[vecin]=nod;
                q.push(vecin);
            }
        }
    }
    if(!vis[d])
    {
        return 0;
    }
    vector<int>path;
    int x=d;
    while(x!=0)
    {
        path.push_back(x);
        x=p[x];
    }
    reverse(path.begin(),path.end());
    int flow = 1e9;
    for(int i=0;i<path.size()-1;i++)
    {
        int a=path[i];
        int b=path[i+1];
        flow=min(flow,capacitate[a][b]-flux[a][b]);
    }
    for(int i=0;i<path.size()-1;i++)
    {
        int a=path[i];
        int b=path[i+1];
        flux[a][b]+=flow;
        flux[b][a]-=flow;
    }
    return flow;
}

int main()
{
    f>>n>>m;
    for(int i=1;i<=m;i++)
    {
        int x,y,c;
        f>>x>>y>>c;
        capacitate[x][y]=c;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    int maxflow=0;
    while(true)
    {
        int flow=bfs(1,n);
        if(flow==0)
            break;
        maxflow+=flow;
    }
    g<<maxflow;
    return 0;
}