Cod sursa(job #1384550)

Utilizator bogdanboboc97Bogdan Boboc bogdanboboc97 Data 11 martie 2015 10:35:06
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.44 kb
#include <fstream>
#include <vector>
#include <algorithm>
#include <limits>
#include <queue>
#define mp make_pair
#define pb push_back
#define INF numeric_limits<int>::max()
#define int64 long long
using namespace std;
ifstream in("maxflow.in");
ofstream out("maxflow.out");
vector< vector<int> > a;
queue<int> q;
int flow[1005][1005],n,k,s,d,maxflow,t[1005],f[1005];
//bfs
void bfs(int start)
{
    for(int i=1;i<=n;i++)t[i]=0;
    k=0;
    t[s]=s;
    q.push(start);
    while(!q.empty())
    {
        int x=q.front();q.pop();
        for(vector<int>::iterator i=a[x].begin();i!=a[x].end();i++)
        if(t[*i]==0 && flow[x][*i]>0)
        {
            if(*i==d)
            {
                f[++k]=x;
                continue;
            }
            t[*i]=x;
            q.push(*i);
        }
    }
}
int main()
{
    int m;
    in>>n>>m;
    a=vector< vector<int> > (n+1);
    for(;m;m--)
    {
        int x,y,z;
        in>>x>>y>>z;
        a[x].pb(y);
        a[y].pb(x);
        flow[x][y]=z;
    }
    for(s=1,d=n;;)//sursa, destinatie
    {
        bfs(s);
        if(k==0)break;
        for(int i=1;i<=k;i++)
        {
            int mx=INF;
            t[d]=f[i];

            for(int x=d;t[x]!=x;x=t[x])
            mx=min(mx,flow[t[x]][x]);

            for(int x=d;t[x]!=x;x=t[x])
            {
                flow[t[x]][x]-=mx;
                flow[x][t[x]]+=mx;
            }

            maxflow+=mx;
        }
    }
    out<<maxflow;
    return 0;
}