Cod sursă (job #582160)

#include <cstdio>

#define MAX_N 200000
#define MAX_DEPTH 1000

using namespace std;

FILE *f, *g;

int n, root;

int st[MAX_N + 1];
int dr[MAX_N + 1];

void readFile()
{
    f = fopen("pointeri.in", "r");

    fscanf(f, "%d%d", &n, &root);

    root ++;

    int i;
    for(i = 1; i <= n; i ++)
    {
        fscanf(f, "%d", &st[i]);

        st[i] ++;
    }

    for(i = 1; i <= n; i ++)
    {
        fscanf(f, "%d", &dr[i]);

        dr[i] ++;
    }

    fclose(f);
}

int first;

int stk[MAX_DEPTH + 1];

void doOrder(int cr, int &last)
{
    if(cr <= 0)
        return;

    doOrder(st[cr], last);

    if(last > 0)
    {
        st[cr] = last;
        dr[last] = cr;
    }

    last = cr;

    doOrder(dr[cr], last);
}

void solve()
{
    int last = -1;

    doOrder(root, last);
}

void afis(int v[])
{
    int i;
    for(i = 1; i <= n; i ++)
    {
        fprintf(g, "%d ", v[i] - 1);
    }

    fprintf(g, "\n");
}

void getFirst()
{
    int i;
    i = 1;
    while(i <= n && st[i] > 0)
        i ++;

    first = i;
}

void printFile()
{
    g = fopen("pointeri.out", "w");

    getFirst();

    fprintf(g, "%d\n", first - 1);

    afis(st);
    afis(dr);

    fclose(g);
}

int main()
{
    readFile();

    solve();

    printFile();

    return 0;
}