Best code - subject 1

#include<cstdio>
#include<vector>
#include<cstdlib>
#define min(a,b) a<b?a:b
using namespace std;
vector<pair<int,int> >V[10010];
vector<pair<int,int> >poz[10010];
int n,A[10010],B[10010],i,vizS[10010],vizJ[10010],nr,cost,a,b,c,d,COST,contor;
void solve(int,int);
int main()
{
    freopen("biperm.in","r",stdin);
    freopen("biperm.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++)scanf("%d",&A[i]);
    for(i=1;i<=n;i++)scanf("%d",&B[i]);
    vizS[0]=vizJ[0]=1;
    for(i=1;i<=n;i++)
    {
        V[A[i]].push_back(make_pair(B[i],i));
        V[B[i]].push_back(make_pair(A[i],-i));
    }
    nr=1;
    for(i=1;i<=n;i++)
    {
        if(!vizS[i])
        {
            contor=0;
            cost=0;
            nr*=2;
            a=V[i].front().first;
            b=V[i].front().second;
            if(b<0)
            {
                vector<pair<int,int> >::iterator it=V[i].begin()+1;
                c=it->first;
                d=it->second;
                if(d<0){cost+=1;solve(i,a);poz[abs(b)].push_back(make_pair(i,a));} else {solve(i,c);poz[abs(d)].push_back(make_pair(i,c));}
            } else {solve(i,a);poz[abs(b)].push_back(make_pair(i,a));}
            COST+=min(cost,contor-cost);
        }
    }
    cost=min(COST,n-COST);
    printf("%d %d\n",nr,cost);
    for(i=1;i<=n;i++)
    {
        if(!poz[i].size())continue;
        a=poz[i].front().first;
        printf("%d ",a);
    }
    printf("\n");
    for(i=1;i<=n;i++)
    {
        if(!poz[i].size())continue;
        a=poz[i].front().second;
        printf("%d ",a);
    }
    return 0;
}
void solve(int X,int Y)
{
    int a,b,c,d;
    vizS[X]=1;vizJ[Y]=1;
    contor++;
    vector<pair<int,int> >::iterator it=V[Y].begin();
    a=it->first;b=it->second;
    if(a==X)a=0;
    it++;
    c=it->first;d=it->second;
    if(c==X&&a!=0)c=0;
    if(vizS[Y])
    {
        if(vizS[a])
        {
            if(!vizS[c])
            {
                cost+=d>0?1:0;
                poz[abs(d)].push_back(make_pair(c,Y));
                solve(c,Y);
            }
        } else
        {
        cost+=b>0?1:0;
        poz[abs(b)].push_back(make_pair(a,Y));
        solve(a,Y);
        }
    }
    if(!vizS[Y])
    {
        if(vizJ[a])
        {
            if(!vizJ[c])
            {
                cost+=d>0?0:1;
                poz[abs(d)].push_back(make_pair(Y,c));
                solve(Y,c);
            }
        }else
        {
            cost+=b>0?0:1;
            poz[abs(b)].push_back(make_pair(Y,a));
            solve(Y,a);
        }
    }
}

//TIA!!!!!!!!