Cod sursă (job #77649)

#include <stdio.h>
#define M 200001
int st[M] ,dr[M];
int poz ,pr ,prec ,radacina;
void parcarb(int poz)
{
    if (poz==-1) return ;
    parcarb( st[poz] );
    if(prec==-1) pr = poz;
    else (dr[prec]=poz);
    st[poz]=prec;
    prec=poz;
    parcarb( dr[poz] );//parcurg arborele recursiv
}
FILE *fin ,*fout;
int n;
int main(){

    fin = fopen("pointeri.in" ,"r");
    fout = fopen("pointeri.out" ,"w");
    int i;
    fscanf(fin ,"%d%d" , &n , &radacina);
    prec=-1;
    for(i=0;i<n;i++)
    {
        fscanf(fin ,"%d" , &st[i]);
    }
    for(i=0;i<n;i++)
    {
        fscanf(fin ,"%d" , &dr[i]);
    }
    parcarb(radacina);
    fprintf(fout ,"%d\n" , pr);
    for(i=0;i<n;i++)
    {
        fprintf(fout ,"%d " , st[i]);
    }
    fprintf(fout ,"\n");
    for(i=0;i<n;i++)
    {
        fprintf(fout ,"%d " , dr[i]);
    }
    return 0;
}