Recursion in binary tree to traverse the entire tree

Question

I am studying binary trees. I saw online a code to traverse the entire binary tree. Here's the code I got: '''

public void showAll(Node node)
{
    Node parent = node;
    if(parent != null)
    {
        System.out.println(" " + parent.person);
        showAll(parent.leftChild);
        showAll(parent.rightChild);
    }
}

'''

What I dont understand is how this function can print the right child? According to code everytime the function is called left child is printed. The code never reaches the right child.

See https://stackoverflow.com/questions/15306452/traversing-through-all-nodes-of-a-binary-tree-in-java for correct code. — PM 77-1, Dec 11 '20 at 21:28

score 0 · Answer 1 · answered Dec 11 '20 at 20:43

This is a textbook implementation of postorder traversal. Also known by some as "bottom up" traversal.

For each iteration the leftmost node then the rightmost node is printed. If the parent node is ever null then the tree is past the highest node, i.e. the algorithm has finished.

score -2 · Answer 2 · answered Dec 11 '20 at 20:36

-2

Try to dry run the code with binary tree having, say 5 nodes. And then you'll probably figure it out. Even then if you are facing problems, learn a little about how a compiler calls functions or what actually stacktrace is.

answered Dec 11 '20 at 20:36

Vidit Singh Brahmania

1
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"Try it and figure it out" is not really an answer – NotZack Dec 11 '20 at 20:38

Recursion in binary tree to traverse the entire tree

2 Answers2