In a preorder traversal of a binary tree, after visiting a node and before moving to the right subtree, we must save a pointer to the node so that after visiting the right subtree, we can visit the left subtree.

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In a preorder traversal of a binary tree, the order of visitation is: visit the node, then traverse the left subtree, and finally traverse the right subtree. There is no need to save a pointer to the node before moving to the right subtree because the left subtree is visited immediately after the node itself, before visiting the right subtree.

In a Preorder Traversal of a Binary Tree, After Visiting