Cod sursa(job #3041969)

Utilizator Zed1YasuoAlex Birsan Zed1Yasuo Data 3 aprilie 2023 11:28:59
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.58 kb
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream f("maxflow.in");
ofstream g("maxflow.out");
int n,m,ans;
const int N=1e3+5;
vector<int>a[N];
bool viz[N];
int nr[N],tt[N],niv[N];
int d[N][N];
void bfs()
{
    for(int i=1;i<=n;i++)
    {
        viz[i]=0;
        niv[i]=-1;
    }
    niv[1]=0;
    queue<int>q;
    q.push(1);
    while(!q.empty())
    {
        int nod=q.front();
        q.pop();
        for(auto x: a[nod])
            if(niv[x]==-1&&d[nod][x]>0)
            {
                niv[x]=niv[nod]+1;
                q.push(x);
                if(x==n)
                    return;
            }
    }
}
int dfs(int nod,int mn)
{
    if(mn==0||nod==n)
        return mn;
    for(auto x:a[nod])
        if(d[nod][x]>0&&niv[x]==niv[nod]+1)
        {
            int R=dfs(x,min(mn,d[nod][x]));
            if(R>0)
            {
                d[nod][x]-=R;
                d[x][nod]+=R;
                return R;
            }
        }
    return 0;
}
bool flux()
{
    bfs();
    if(niv[n]==-1)
        return 0;
    int val=0;
    while(true)
    {
        int x=dfs(1,1e9);
        if(x==0)
            break;
        val+=x;
    }
    ans+=val;
    if(val!=0)
        return 1;

    return false;
}
int main()
{
    f>>n>>m;
    int x,y,z;
    for(int i=1;i<=m;i++)
    {
        f>>x>>y>>z;
        a[x].push_back(y);
        a[y].push_back(x);
        d[x][y]=z;
    }
    while(flux());
    g<<ans;
    return 0;
}