lecture13

# lecture13 - Monday March 1 st • Binary Tree Traversals...

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Unformatted text preview: Monday, March 1 st • Binary Tree Traversals • Using Binary Trees to Evaluate Expressions • Binary Search Trees • Binary Search Tree Operations – Searching for an item – Inserting a new item – Finding the minimum and maximum items – Printing out the items in order – Deleting the whole tree Binary Tree Traversals When we process all the nodes in a tree, it’s called a traversal. There are four common ways to traverse a tree. 1. Pre-order traversal 2. In-order traversal 3. Post-order traversal 4. Level-order traversal Preorder : 1. Process the current node. 2. Process the nodes in the left sub-tree. 3. Process the nodes in the right sub-tree. The Preorder Traversal Preorder : 1. Process the current node. 2. Process the nodes in the left sub-tree. 3. Process the nodes in the right sub-tree. By “ process the current node ” we typically mean one of the following: 1. Print the current node’s value out. 2. Search the current node to see if its value matches the one you’re searching for. 3. Add the current node’s value to a total for the tree 4. Etc… void PreOrder(Node *cur) { if (cur == NULL) // if empty, return… return; cout << cur->value; // Process the current node. PreOrder(cur->left); // Process nodes in left sub-tree . PreOrder(cur-> right); // Process nodes in left sub-tree . } main() { Node *root; … PreOrder(root); } NULL “a” “b” “c ” NULL “d” NULL NULL NULL “e ” NULL ro o t c ur O utput: a C ur po ints to “a ” vo id Pre O rde r(No de *c ur) { if (c ur == NULL) // if e m pty, re turn… re turn; cout << cur->value; // Process the current node. PreOrder(cur->left); // Process nodes in left sub-tree . PreOrder(cur-> right); // Process nodes in left sub-tree . } cur Cur points to “b” b The Pre-order Traversal void PreOrder(Node *cur) { if (cur == NULL) // if empty, return… return; cout << cur->value; // Process the current node. PreOrder(cur->left); // Process nodes in left sub-tree . PreOrder(cur-> right); // Process nodes in left sub-tree . } Cur points to “d” cur d void PreOrder(Node *cur) { if (cur == NULL) // if empty, return… return; cout << cur->value; // Process the current node....
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## This note was uploaded on 04/10/2012 for the course CS 32 taught by Professor Davidsmallberg during the Winter '08 term at UCLA.

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lecture13 - Monday March 1 st • Binary Tree Traversals...

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