Question

          a
        /    \ 
       a       a
      / \     /  \
     a   c    a   f 
    / \      / \ 
   b   d    e   g

I have a tree that looks like the above, represented by a linked structure:

   class Node
    {
       Node* leftChild; 
       Node* rightChild; 
       char data;
    }

class Tree
{
   Node* root;
}

My goal is to find all the paths from the root to leaf nodes.

My tree traversal algorithm looks like this:

 void inorder()
  {
    in(root);
  }

  void in(CharNode* currentNode)
  {
    if(currentNode)
      {   
        in(currentNode->leftChild);
        cout << currentNode->data << endl;
        in(currentNode->rightChild);
      }   
  }

When I run this, I am positive that the tree is being built as shown. I have tested that. I cannot, however, figure out why my tree traversal segmentation faults.

The output I get is :

b

Segmentation fault.

I have tested it on trees with smaller heights, and it works. But for some reason it doesn’t work on a trees with heights larger than 2. I thought it was something going wrong with the tree, I have gone through and printed each parent, left child, and right child and they print out as shown. So it’s definitely the traversal algorithm.

Answer 1

As you build your tree, be sure to initialize leftChild and rightChild to NULL (0) on your nodes. This is critical for leaf-nodes and for nodes missing either a leftChild or a rightChild.

class Node
      : leftChild(0)
      , rightChild(0)
      , data(0)
{
   Node* leftChild; 
   Node* rightChild; 
   char data;
}