Cod sursa(job #1144539)

Utilizator kiralalaChitoraga Dumitru kiralala Data 17 martie 2014 11:34:15
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.97 kb
#include <fstream>
#include <queue>
#include <vector>
#define INF 999999999
#define NMAX 1005

using namespace std;

FILE* f=freopen("maxflow.in","r",stdin);
FILE* o=freopen("maxflow.out","w",stdout);

int n,m;
int flow;
int father[NMAX];
int cap[NMAX][NMAX],flw[NMAX][NMAX];
vector<int> graph[NMAX];

inline void INIT(int a[],int v, int n)
{
    for(int i=0;i<=n;++i) a[i]=v;
}
inline int minim(int a, int b) { return (a<b)?a:b; }

int MoreFlow()
{
    queue<int> q;
    INIT(father,0,n);

    q.push(1);
    father[1]=-1;
    int x;
    while(!q.empty())
    {
        x=q.front();
        q.pop();
        if(x==n) continue;
        for(int i=0;i<graph[x].size();++i)
        {
            int ind=graph[x][i];
            if(cap[x][ind]==flw[x][ind]||father[ind]) continue;
            father[ind]=x;
            q.push(ind);
        }
    }
    return father[n];
}

void MaxFlow()
{
    for(flow=0;MoreFlow();)
    {
        for(int i=0;i<graph[n].size();++i)
        {
            int where=graph[n][i];
            if(cap[where][n]==flw[where][n]||!father[where]) continue;
            father[n]=where;
            int minflow=INF;
            for(where=n;where!=1;where=father[where])
            {
                int ft=father[where];
                minflow=minim(minflow,cap[ft][where]-flw[ft][where]);
            }
            if(minflow>0)
            {
                for(where=n;where!=1;where=father[where])
                {
                    int ft=father[where];
                    flw[ft][where]+=minflow;
                    flw[where][ft]-=minflow;
                }
            }
            flow+=minflow;
        }
    }
}

int main()
{
    scanf("%d%d",&n,&m);

    for(int i=0;i<m;++i)
    {
        int x,y,c;
        scanf("%d%d%d",&x,&y,&c);

        cap[x][y]=+c;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }

    MaxFlow();

    printf("%d",flow);

    return 0;
}