1. Week 14 - Wednesday

2.  What did we talk about last time?  Heapsort  Timsort  Counting sort  Radix sort

6. Student Lecture

8.  We can use a (non-binary) tree to record strings implicitly where each link corresponds to the next letter in the string  Let’s store:  ba  bar  bat  barry  can  candle  as

9. a s b a r r y t c a n d l e

10.  Now you add:  he  she  her  help  sat  rat

11. public class Trie { private static class TrieNode { public char letter; public boolean terminal; public TrieNode[] children; } private TrieNode root; public Trie() { root = new TrieNode(); root.letter = ' '; root.terminal = false; root.children = null; }

12. Signature for recursive method: private static boolean contains(TrieNode node, String word, int index) Called by public proxy method: public boolean contains(String word) { return contains(root, word, 0); }

13. Signature for recursive method: private static void insert(TrieNode node, String word, int index) Called by public proxy method: public void insert(String word) { insert(root, word, 0); }

14. private static void inorder(TrieNode node, String prefix) if( node.terminal ) System.out.println(prefix); if( node.children != null ) for( TrieNode child : node.children ) inorder(child, prefix + child.letter); } Called by public proxy method: public void inorder(String word) { inorder(root, ""); }

15.  Let m be the length of a particular string  Find Costs:  O(m)  Insert Costs:  O(m)

18.  Review up to Exam 1!  IDEA forms

19.  Work on Project 4  Work on Assignment 7  Due when you return from Thanksgiving