- Visit the root node
- traverse the left sub-tree in pre-order
- traverse the right sub-tree in pre-order
- Step 1: Repeat Steps 2 to 4 while TREE != NULL
- Step 2: Write TREE -> DATA
- Step 3: PREORDER(TREE -> LEFT)
- Step 4: PREORDER(TREE -> RIGHT)
[END OF LOOP]
- Step 5: END
Traverse the following binary tree by using pre-order traversal
- Since, the traversal scheme, we are using is pre-order traversal, therefore, the first element to be printed is 18.
- traverse the left sub-tree recursively. The root node of the left sub-tree is 211, print it and move to left.
- Left is empty therefore print the right children and move to the right sub-tree of the root.
- 20 is the root of sub-tree therefore, print it and move to its left. Since left sub-tree is empty therefore move to the right and print the only element present there i.e. 190.
- Therefore, the printing sequence will be 18, 211, 90, 20, 190.