Cod sursa(job #1172037)

Utilizator iordache.bogdanIordache Ioan-Bogdan iordache.bogdan Data 16 aprilie 2014 18:06:22
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.53 kb
#include <fstream>
#include <cstring>
#include <vector>
#define INF 1000000000

using namespace std;

ifstream f("maxflow.in");
ofstream g("maxflow.out");

vector<int> L[1005];
vector<int>::iterator it;

int n,m,i,p,u,nod,x,y,Min,z,flux;

int q[10005],C[1005][1005],F[1005][1005],T[1005];

bool viz[1005];

inline int minim(int a, int b) {
    return a<b ? a : b;
}

bool BFS() {
    p=u=1;
    q[1]=1;
    memset(viz,0,n+1);
    viz[1]=1;
    while (p<=u) {
        if(q[p]==n) {
            p++;
            continue;
        }
        nod=q[p];
        for(it=L[nod].begin();it!=L[nod].end();it++) {
            if(viz[*it] || C[nod][*it]==F[nod][*it])
                continue;
            viz[*it]=1;
            u++;
            q[u]=*it;
            T[*it]=nod;
        }
        p++;
    }
    return viz[n];
}

int main() {
    f>>n>>m;
    for(i=1;i<=m;i++) {
        f>>x>>y>>z;
        C[x][y]=z;
        L[x].push_back(y);
        L[y].push_back(x);
    }

    while( BFS() ) {
        for(it=L[n].begin();it!=L[n].end();it++) {
            if(!viz[*it] || C[*it][n]==F[*it][n])
                continue;
            T[n]=*it;
            Min=INF;
            for(i=n;i!=1;i=T[i])
                Min=minim(Min,C[T[i]][i]-F[T[i]][i]);
            if(Min==0)
                continue;
            for(i=n;i!=1;i=T[i]) {
                F[T[i]][i]+=Min;
                F[i][T[i]]-=Min;
            }
            flux+=Min;
        }
    }
    g<<flux<<"\n";
    return 0;
}