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Binary Search Tree
OBJECTIVES
1. Build a binary search tree (BST)
2. Search and Traverse a BST
Background
In 2009, Netflix held a competition to see who could best predict user ratings for films based on previous ratings without any other information about the users or films. The grand prize of US$1,000,000 was given to the BellKor's Pragmatic Chaos team which bested Netflix's own algorithm for predicting ratings by 10.06%. This kind of data science is facilitated with the application of good data structures. In fact, cleaning and arranging data in a conducive manner is half the battle in making successful predictions. Imagine you are attempting to predict user ratings given a dataset of IMDB’s top 100 movies. Building a binary search tree will enable you to search for movies and extract their features very efficiently. The movies will be accessed by their titles, but they will also store the following features:
• IMDB ranking (1-100)
• Title
• Year released
• IMDB average rating
Your binary search tree will utilize the following struct with default and overloaded constructors:
structMovieNode{
int ranking;
string title;
int year;
float rating;
MovieNode* left = NULL;
MovieNode* right = NULL;
};
CSCI 2270 – Data Structures
Instructors:
MovieTree Class
Your code should implement a binary search tree of MovieNode data type. A header file that lays out this tree can be found in MovieTree.hpp on Moodle. As usual, DO NOT modify the header file. You may implement helper functions in your .cpp file to facilitate recursion if you want as long as you don’t add those functions to the MovieTree class.
MovieTree()
• Constructor: Initialize any member variables of the class to default
~MovieTree()
• Destructor: Free all memory that was allocated
void printMovieInventory()
• Print every node in the tree in alphabetical order of titles using the following format:
// for every Movie node (m) in the tree
cout << "Movie: "<< m->title << " "<< m->rating << endl;
If there is no movie entry in the tree, print the following message instead:
cout << "Tree is Empty. Cannot print"<< endl;
void addMovieNode(int ranking,std::string title,int year,float rating)
• Add a node to the tree in the correct place based on its title.Every node’s left children should come before it alphabetically, and every node’s right children should come after it alphabetically. Hint: you can compare strings with <, >, ==, string::compare() function.
• For example,if the root node of the tree is the movie “Forrest Gump”, then the movie “Iron Man” should be in the root's right subtree and “Aladdin” should be in its left subtree.
• You can assume that no two movies have the same title
void findMovie(string title)
• Find the movie with the given title,then print out its information:
cout <<"Movie Info:"<<endl;
cout <<"=================="<<endl;
cout <<"Ranking:"<< node->ranking <<endl; cout <<"Title :"<< node->title <<endl; cout <<"Year :"<< node->year <<endl; cout <<"rating :"<< node->rating <<endl;
If the movie isn’t found, print the following message instead:
CSCI 2270 – Data Structures
Instructors:
cout<< "Movie not found."<< endl;
void queryMovies(float rating,int year)
• Print all the movies whose rating is at least as good as the input parameter rating and that are newer than yearin the preorderfashionusing the following format:
cout<< "Movies that came out after " << year <<" with rating at least " << rating <<":"<< endl;
• each movie that satisfies the constraints should be printed with cout << m->title << "(" << m->year << ") "<< m->rating << endl;
If there is no movie entry in the tree, print the following message instead:
cout << "Tree is Empty. Cannot query Movies"<< endl;
void averageRating()
• Print the average rating for all movies in the tree. If the tree is empty, print 0.0. Use the following format:
cout << "Average rating:" << average << endl;
If there is no movie entry in the tree, print the following message instead:
cout << "Average rating:0.0"<< endl;
CSCI 2270 – Data Structures
Instructors:
void printLevelNodes(intlevel)
• Print all the nodes in the tree from left to right that are exactly at depth = level from the root of the tree. If the user passes a level value which is more than the maximum depth of the tree, then don't print anything and just exit the function.
// for every Movie node (m) in the tree
cout << "Movie: "<< m->title << " "<< m->rating << endl;
• For example,for the tree below, if level = 2, your function should print the title and rating for Akira, Batman and Hercules in that order (nodes from left to right at depth=2 from the root node of the tree).
Driver
For this assignment, the driver code has been provided to you in the Driver.cppfile. The main function will read information about each movie from a CSV file and store that information in a MovieTree using your addMovieNodefunction implementation.
The name of the CSV file with this information should be passed in as a command-line argument.Example files are Movies.csv,Documentaries.csvon Moodle in the format:
<Movie 1 ranking>,<Movie 1 title>,<Movie 1 year>,<Movie 1 rating> <Movie 2 ranking>,<Movie 2 title>,<Movie 2 year>,<Movie 2 rating> Etc…
CSCI 2270 – Data Structures
Instructors:
Afterreading the information on each movie from the file and building the tree, the user is displayed the following menu:
======Main Menu======
1. Find a movie
2. Query movies
3. Print the inventory
4. Average Rating of movies
5. Print movies at Level k
6. Quit
The menu options have the following behavior:
• Find a movie: Calls your tree’s findMovie function on a movie specified by the user. The user is prompted for a movie title.
• Query movies: Calls your tree’s queryMoviesfunction on a rating and year specified by the user. Prompts the user for a rating and year.
• Print the inventory: Call your tree’s printMovieInventoryfunction
• Average Rating of movies: Calls your tree’s averageRating function
• Print movies at Level k:Calls your tree’s printLevelNodesfunction on the level specified by the user. The user is prompted for a level.
• Quit: Program exits after printing a friendly message to the user.
