Problem p02279 (C++) — buggy submission, verdict: Runtime Error

#include <iostream>
#include <stdlib.h>
using namespace std;

struct Node {
  int parent;
  int number;
  struct Node *left;
  struct Node *right;
};

struct Node *N[100000];
// void show()
//
int getDepth(struct Node *node) {

  int count = 0;

  while (node->parent != -1) {
    count++;
    node = N[node->parent];
  }

  return count;
}

int main() {

  struct Node *node1, *node2, *node3, *prev_node, *parent;
  int n, m, node, parent_number, node_count, child_node;

  cin >> n;

  for (int i = 0; i < n; i++) {
    N[i] = NULL;
  }
  for (int i = 0; i < n; i++) {
    cin >> parent_number;
    cin >> node_count;

    if (N[parent_number] == NULL) {
      node2 = (struct Node *)malloc(sizeof(struct Node));
      node2->number = parent_number;
      node2->right = NULL;
      node2->left = NULL;
      node2->parent = -1;
      N[parent_number] = node2;
    }

    for (int j = 0; j < node_count; j++) {
      cin >> child_node;
      node1 = (struct Node *)malloc(sizeof(struct Node));
      node1->number = child_node;

      // slibing
      if (j == 0) {
        N[parent_number]->left = node1;
      } else {
        prev_node->right = node1;
      }

      // parent
      node1->parent = parent_number;

      prev_node = node1;
      // cout << prev_node->number << endl;

      if (N[child_node] == NULL) {

        node1->right = NULL;
        node1->left = NULL;
        N[child_node] = node1;
      }
      // else {

      //}
      // cout << "child node " << parent_number;
      N[child_node]->parent = parent_number;
    }
  }
  for (int i = 0; i < n; i++) {
    struct Node *a = N[i];
    struct Node *b;
    cout << "node " << i << ":";
    cout << " parent = " << a->parent;

    // depth
    //
    cout << ", depth = ";
    cout << getDepth(a);

    // type
    if (a->parent == -1) {
      cout << ", root";
    } else if (a->left) {
      cout << ", internal node";
    } else if (a->left == NULL) {
      cout << ", leaf";
    }

    cout << ", [";
    b = a->left;
    while (b != NULL) {
      cout << b->number;
      b = b->right;
      if (b) {
        cout << ", ";
      }
    }
    cout << "]";

    cout << endl;
  }

  return 0;
}


Error: 0

Fixed submission:

#include <iostream>
#include <stdlib.h>
using namespace std;

struct Node {
  int parent;
  int number;
  struct Node *left;
  struct Node *right;
};

struct Node *N[10000];
// void show()
//
int getDepth(struct Node *node) {

  int count = 0;

  while (node->parent != -1) {
    count++;
    node = N[node->parent];
  }

  return count;
}

int main() {

  struct Node *node1, *node2, *node3, *prev_node, *parent;
  int n, m, node, parent_number, node_count, child_node;

  cin >> n;

  for (int i = 0; i < n; i++) {
    N[i] = NULL;
  }
  for (int i = 0; i < n; i++) {
    cin >> parent_number;
    cin >> node_count;

    if (N[parent_number] == NULL) {
      node2 = (struct Node *)malloc(sizeof(struct Node));
      node2->number = parent_number;
      node2->right = NULL;
      node2->left = NULL;
      node2->parent = -1;
      N[parent_number] = node2;
    }

    for (int j = 0; j < node_count; j++) {
      cin >> child_node;
      node1 = (struct Node *)malloc(sizeof(struct Node));
      node1->number = child_node;

      // slibing
      if (j == 0) {
        N[parent_number]->left = node1;
      } else {
        prev_node->right = node1;
      }

      // parent
      node1->parent = parent_number;

      prev_node = node1;
      // cout << prev_node->number << endl;

      if (N[child_node] == NULL) {

        node1->right = NULL;
        node1->left = NULL;
        N[child_node] = node1;
      }
      // else {

      //}
      // cout << "child node " << parent_number;
      N[child_node]->parent = parent_number;
    }
  }
  for (int i = 0; i < n; i++) {
    struct Node *a = N[i];
    struct Node *b;
    cout << "node " << i << ":";
    cout << " parent = " << a->parent;

    // depth
    //
    cout << ", depth = ";
    cout << getDepth(a);

    // type
    if (a->parent == -1) {
      cout << ", root";
    } else if (a->left) {
      cout << ", internal node";
    } else if (a->left == NULL) {
      cout << ", leaf";
    }

    cout << ", [";
    b = a->left;
    while (b != NULL) {
      cout << b->number;
      b = b->right;
      if (b) {
        cout << ", ";
      }
    }
    cout << "]";

    cout << endl;
  }

  return 0;
}