hwk06 - The homework files include a class1based...

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Unformatted text preview: The homework files include a class1based implementation of a Stack ADT. The items in this stack can only be of integer type. You must modify this implementation using templates to allow the Stack ADT to contain any data type. A main.cpp file is provided to test your implementation. The expected output is the following: 9 8 7 6 5 4 3 2 1 First element is 9 9 8 7 6 5 4 3 2 1 Popped element 9 8 7 6 5 4 3 2 1 Popped element 8 7 6 5 4 3 2 1 Popped element 7 6 5 4 3 2 1 Popped element 6 5 4 3 2 1 Popped element 5 4 3 2 1 Popped element 4 3 2 1 Popped element 3 2 1 Popped element 2 1 Popped element 1 Stack is empty! 5 4 3 2 1 8 7 6 5 4 3 2 1 Exercise 1 <<15 points>> CMSC 152001 Intro to Computer Science 2 Summer 2009 Homework #6 (8/14/2009) Due Date: 8/19/2009 (before class 11 1:30 pm) Exercise 2 <<20 points>> PhoneCorp and PhoneTech, the two biggest phone companies in the US, have just completed a corporate merger. They are now faced with the daunting task of merging their client data files into a single file. In particular, each company has a text file with the social security numbers of their clients (one 91digit number in each line) in increasing order. Your task is to create a program that takes those two files and creates a new file with the numbers from both files, in increasing order. You can assume that the two file have no numbers in common (i.e. the two sets of clients are disjoint) For example: For example: Your program must be run like this: ex1 <clientfile1> <clientfile2> <result> A skeleton ex2.cpp file is provided showing how to retrieve the command1line parameters. For full credit (10 points otherwise), your file must perform the merge doing a single pass through each of the files, without loading them into memory. Note: Two example files (clients1 and clients2) are provided in the homework files. The result of correctly merging these two files is the following: 113624982 135648623 154564564 168943568 193215689 236584654 276546846 279461322 283216569 295464654 316243213 333218954 342654658 345654858 393546562 395221354 399321545 412135468 422354943 462213589 493215812 539565482 539635482 783213542 896546543 973213215 993219953 Hint 2: This is a good example of an exercise you should try to first solve with a more reduced problem set, before approaching the complete problem. For example, to familiarize yourself with the merging algorithm (without dealing with all the I/O messiness), try merging two 51position arrays (preloaded with any integers you want, as long as they are in increasing order) into a 101position array. When you do start to add the I/O code, first give your algorithm a try with smaller files than the ones provided (with single1digit integers, for example, which are easier to check than 91digit numbers). Hint 2: This is a good example of an exercise you should try to first solve with a more reduced problem set, before approaching the complete problem. For example, to familiarize yourself with the merging algorithm (without dealing with all the I/O messiness), try merging two 51position arrays (preloaded with any integers you want, as long as they are in increasing order) into a 101position array. When you do start to add the I/O code, first give your algorithm a try with smaller files than the ones provided (with single1digit integers, for example, which are easier to check than 91digit numbers). Exercise 3 <<5 points>> Make a simple modification to Exercise 1 so that you program will be able to handle files with common numbers (i.e. the two companies share some clients in common, so the two sets of clients are not disjoint). For example: Note: Two example files (clients1_rep and clients2_rep) are provided in the homework files. The result of correctly merging these two files is the following: 113624982 135648623 168943568 236584654 256684623 276546846 279461322 295464654 316243213 333218954 342654658 345654858 356698823 393546562 395221354 399321545 399645652 412135468 419654332 422354943 462213589 539565482 539635482 712315465 896546543 936532132 946546523 982132132 983213223 In the remaining exercises you will add missing functionality to a Binary Search Tree implementation.The structure and function declarations are the following (tree.h in the homework files): struct TreeNode { TreeNode* left; int value; TreeNode* right; }; typedef TreeNode* Tree; void createTree(Tree &t); bool insert(Tree &t, int value); void inorder(Tree &t); void preorder(Tree &t); void postorder(Tree &t); bool find(Tree &t, int value); int height(Tree &t); bool remove(Tree &t, int value); To test your tree implementation, a main.cpp is provided in the homework files. Running this program with all the exercises correctly implemented should yield the following: CREATING AND INSERTING 1111111111111111111111 Could not insert value Could not insert value Could not insert value The height of the tree 15. Already in tree. 17. Already in tree. 23. Already in tree. is 3 TRAVERSALS 1111111111 4 10 12 13 15 17 23 25 29 15 10 4 13 12 23 17 29 25 4 12 13 10 17 25 29 23 15 BINARY SEARCH 1111111111111 Value 10 is contained in the tree. Value 29 is contained in the tree. Value 48 is NOT contained in the tree. REMOVAL OF NODES 1111111111111111 4 10 12 13 15 17 23 25 29 Removing node 25: 4 10 12 13 15 17 23 29 4 10 12 13 15 The height of Removing node 4 10 12 15 17 The height of Removing node 4 10 12 17 23 The height of 17 23 29 the tree is 3 13: 23 29 the tree is 2 15: 29 the tree is 2 When debugging your program, take into account that the tree used in the main.cpp program is exactly the same as the one shown in the previous page. Exercise 4 <<10 points>> The provided implementation already includes an insert function: bool insert(Tree &t, int value); However, it uses an iterative algorithm, which is not as readable as the recursive version of the algorithm. You must reimplement the insertion algorithm using a recursive algorithm. You are not allowed to modify the expected behaviour of the function, so don't forget that the function must return true if the insertion was successful and false if the tree already contains the specified value. Exercise 5 <<10 points>> Implement the following function: int height(Tree &t); This function returns the height of the tree, which is the length of the path from the root of the tree to the lowest leaf node. Hint: Finding the height is a very simple problem if you come up with a recursive definition of a tree's height. Exercise 6 <<10 points>> Implement the remove function: bool remove(Tree &t, int value); This function removes the node with the specified value. This is more complicated than the deleteSubtree method shown in the book, since we are not just cutting off an entire branch of the tree. We want to remove a specific node, and make sure that the result is still a tree (e.g., think about what would happen if you removed node 23 in the tree what would happen to its left and right subtrees?). The function will return true if the removal was successful and false if no such value was found. This function removes the node with the specified value. This is more complicated than the deleteSubtree method shown in the book, since we are not just cutting off an entire branch of the tree. We want to remove a specific node, and make sure that the result is still a tree (e.g., think about what would happen if you removed node 23 in the tree what would happen to its left and right subtrees?). The function will return true if the removal was successful and false if no such value was found. When removing a node from the tree, you will encounter three different scenarios: Removing a leaf This is the simplest case. Simple free the memory allocated to the node, and make sure you update the parent node to indicate that it no longer has a subtree. Removing a node with a single child In this case, we will need to give the orphaned child a new parent. We just need to modify the node's parent so its subtree will be the orphaned subtree. Removing a node with two children This is the most complex scenario. If we want to remove a node with two children, the first thing we need to do is find the largest node of all the nodes in the left1subtree ("largest of smaller", or LoS). For example let's suppose we want to remove node 15. The largest node in the left sub1tree is 13. We must change the value of the node we want to remove to be the value of the LoS. Finally, we will need to remove the LoS node. Take into account that, by definition, the LoS must be a node with a single child or no children, since there are no nodes with values larger than it (i.e., it will not have This is the most complex scenario. If we want to remove a node with two children, the first thing we need to do is find the largest node of all the nodes in the left1subtree ("largest of smaller", or LoS). For example let's suppose we want to remove node 15. The largest node in the left sub1tree is 13. We must change the value of the node we want to remove to be the value of the LoS. Finally, we will need to remove the LoS node. Take into account that, by definition, the LoS must be a node with a single child or no children, since there are no nodes with values larger than it (i.e., it will not have a right subtree). So, we will be able to remove the LoS node using any of the two previous algorithms. Note how, in this case, the node we want to remove doesn't actually get removed (we just change its value to the LoS node's value, and then remove the LoS node). ...
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This note was uploaded on 10/10/2009 for the course CMSC 15200 taught by Professor Paolocodenotti during the Summer '09 term at UChicago.

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