Never Forget Tree Traversal Again — Here’s Why

I’m going to write a short trick to remember inorder, preorder, and postorder.

Do you remember what inorder, preorder, and postorder are?

We all know that their definition is driven by their patterns (root, left, and right).

But how many of you can actually recollect the order properly? Most of you will get confused, even though you know it’s just a simple order.

Photo by Vitaly Gariev on Unsplash

But what if I say I have a trick to remember this order with zero effort?

This article will contain my secret tricks.

Photo by Sreehari Devadas on Unsplash

Most of us would have gone to a temple and prayed to God.

Do you remember which god you will see first after entering the temple? Will it be the main god or Ganapati? Most people know that we will see Ganapati first, as he is placed at the entrance or on the left side of the main god.

Mostly, people see the gods in a clockwise direction, which means we see them from left to right. Most people already know this, but if not, just keep it in mind.

Imagine you are planning to visit the temple and pray to God. Let’s map your visit to tree traversal.

“Think of the main god as Root, Ganapati as Left, and Murugan as Right."

Case 1 — Preorder (Root → Left → Right): Before going to the temple, let’s forget all the temple rules. You plan to visit the main god first. After that, the left side is free, so you see Ganapati next, and finally, you see Murugan on the right. Since you planned this order before entering the temple, it is called a preorder.

Case 2 — Inorder (Left → Root → Right): Inside the temple, you see people moving in a queue from left to right. You ask them why, and they reply, “You need to see Ganapati first, before the main god.” So you follow the crowd: left, then root, then right. Since this happens inside the temple, it is called "inorder."

Case 3 — Postorder (Left → Right → Root): Now, what would you say if someone asked you the order of your visit? It would be confusing, right? Since preorder and inorder were already different, you ended up saying you visited Ganapati first, followed by Murugan, and finally the main god—left, right, then root. Since this happened after you came out of the temple, we call it "postorder" (“post” means “after”).

Next time someone asks you, “Do you know tree traversal?” — just picture yourself planning a visit to the temple.

Hope this real-life trick helps at least a few of you remember tree traversal with less effort, as it uses something we experience in everyday life along with simple, common-sense logic.

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