In this iteration of autocomplete, youll eliminate the weakness of the previous version: a long load time due to slow addition of words to the Autocompleter. Instead of add taking theta(n) worst-case time, you should aim for theta(log n) time. All other methods should retain their current speeds. To achieve this, a more advanced data structure is needed: a binary search tree. The following files have been given to you: 1. A C++ header file (autocompleter.h) declaring the Autocompleter class. 2. A C++ source file (main.cpp) containing a main() function with tests. 3. A text file (words.txt) containing 10000 common words. Create new C++ source file named autocompleter.cpp that implements the function declared in autocompleter.h so that autocompleter.cpp and the provided files compile into a program that runs with no failed tests.

// BEGIN AUTOCOMPLETER.H

#ifndef AUTOCOMPLETER_H #define AUTOCOMPLETER_H

#include

using namespace std;

class Autocompleter { public: // Same as hwAC1 Autocompleter(); void insert(string x); // a.k.a. add() int size(); int completion_count(string x); void completions(string x, string* suggestions);

private: // A helper class that implements // a basic binary search tree node. class Node { public: Node(string s) { this->s = s; left = right = nullptr; }

string s; Node* left; Node* right; };

// Helper method for size() int size_recurse(Node* root); // Helper method for completion_count(). // Here's a (recursive) algorithm: // // Base case: // If root is nullptr, then return 0. // // Recursive case: // -Return the sum of the completion counts of the // left and right subtrees plus: // 0 if root->s does not start with x. // 1 if root->s does start with x. int completion_count_recurse(string x, Node* root);

// Helper method for completions(). // Here's a (recursive) algorithm: // // Base case: // If root is nullptr, return. // If the last entry of the suggestions array is not "", return. // (since completions() has already found 5 suggestions). // // Recursive case: // -Recurse on left subtree. // -If root->s starts with x, add root->s to first empty // location in suggestions. // -Recurse on right subtree. void completions_recurse(string x, string* suggestions, Node* root);

// The data structure should be a binary search tree Node* root; };

#endif

//END AUTOCOMPLETER.H

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//BEGIN MAIN.CPP

#include #include #include #include #include "autocompleter.h"

using namespace std;

inline void _test(const char* expression, const char* file, int line) { cerr << "test(" << expression << ") failed in file " << file; cerr << ", line " << line << "." << endl; abort(); }

#define test(EXPRESSION) ((EXPRESSION) ? (void)0 : _test(#EXPRESSION, __FILE__, __LINE__))

// Used later for testing string random_string(int length) { string s; for (int i = 0; i < length; ++i) s += 'a' + (rand() % 26); return s; }

void interactive_mode() { Autocompleter dictionary;

// Fill autocompleter with words ifstream f; f.open("words.txt"); assert(f.is_open()); // If this fails, you're missing words.txt string line; while (getline(f, line)) dictionary.insert(line); f.close();

string results[5]; while (cin) { string line; getline(cin, line); dictionary.completions(line, results); for (int i = 0; i < 5; ++i) if (results[i] != "") cout << " " << results[i] << endl; } exit(0); }

int main() { srand(2017); // Initialize random number generation, e.g. rand() string results[5]; // Used to hold output suggestions in some tests

// Uncomment line below to use your Autocompleter interactively. // Enter a string and press Enter - the autocompletions // results from the 100000 most common words are printed. // // interactive_mode();

// Test a small Autocompleter with animal names Autocompleter animals; test(animals.size() == 0);

animals.insert("aardvark"); animals.insert("albatross"); animals.insert("alpaca"); animals.insert("armadillo"); animals.insert("camel"); animals.insert("cat"); animals.insert("crocodile"); animals.insert("crow"); animals.insert("giraffe"); animals.insert("goat"); animals.insert("goose"); animals.insert("gorilla"); test(animals.size() == 12);

animals.insert("gorilla"); // Already in the Autocompleter test(animals.size() == 12);

test(animals.completion_count("a") == 4); test(animals.completion_count("al") == 2); test(animals.completion_count("cro") == 2); test(animals.completion_count("gir") == 1); test(animals.completion_count("go") == 3);

test(animals.completion_count("") == 12);

test(animals.completion_count("an") == 0); test(animals.completion_count("q") == 0); test(animals.completion_count("goat-billed carp") == 0);

// Create an autocompleter of common words. Autocompleter dictionary;

// Fill autocompleter with words string* words = new string[100000]; ifstream f; f.open("words.txt"); assert(f.is_open()); // If this fails, you're missing words.txt string line; int i = 0; while (getline(f, line)) { words[i] = line; ++i; } f.close(); assert(i == 100000); // If this fails, words.txt is wrong

for (int i = 0; i < 100000; ++i) dictionary.insert(words[i]); delete[] words;

for (int i = 0; i < 10; ++i) test(dictionary.size() == 100000);

test(dictionary.completion_count("bir") == 55); test(dictionary.completion_count("hap") == 25); test(dictionary.completion_count("program") == 25); test(dictionary.completion_count("foo") == 68);

// Test completions() on animals Autocompleter already made. animals.completions("a", results); test(results[0] == "aardvark"); test(results[1] == "albatross"); test(results[2] == "alpaca"); test(results[3] == "armadillo"); test(results[4] == "");

animals.completions("al", results); test(results[0] == "albatross"); test(results[1] == "alpaca"); test(results[2] == ""); test(results[3] == ""); test(results[4] == "");

animals.completions("cro", results); test(results[0] == "crocodile"); test(results[1] == "crow"); test(results[2] == ""); test(results[3] == ""); test(results[4] == "");

animals.completions("gir", results); test(results[0] == "giraffe"); test(results[1] == ""); test(results[2] == ""); test(results[3] == ""); test(results[4] == "");

animals.completions("go", results); test(results[0] == "goat"); test(results[1] == "goose"); test(results[2] == "gorilla"); test(results[3] == ""); test(results[4] == "");

animals.completions("", results); test(results[0] == "aardvark"); test(results[1] == "albatross"); test(results[2] == "alpaca"); test(results[3] == "armadillo"); test(results[4] == "camel");

animals.completions("an", results); test(results[0] == ""); test(results[1] == ""); test(results[2] == ""); test(results[3] == ""); test(results[4] == "");

animals.completions("q", results); test(results[0] == ""); test(results[1] == ""); test(results[2] == ""); test(results[3] == ""); test(results[4] == "");

animals.completions("goat-billed carp", results); test(results[0] == ""); test(results[1] == ""); test(results[2] == ""); test(results[3] == ""); test(results[4] == "");

// Test completions() on dictionary Autocompleter already made. dictionary.completions("bir", results); test(results[0] == "bir"); test(results[1] == "biracial"); test(results[2] == "birch"); test(results[3] == "birches"); test(results[4] == "birchwood");

dictionary.completions("hap", results); test(results[0] == "hap"); test(results[1] == "haphazard"); test(results[2] == "haphazardly"); test(results[3] == "hapkido"); test(results[4] == "hapless");

dictionary.completions("program", results); test(results[0] == "program"); test(results[1] == "programa"); test(results[2] == "programas"); test(results[3] == "programchecker"); test(results[4] == "programe");

dictionary.completions("foo", results); test(results[0] == "foo"); test(results[1] == "foobar"); test(results[2] == "food"); test(results[3] == "foodborne"); test(results[4] == "foodie");

// Test efficiency of completion_count() and completions() for (int i = 0; i < 10; ++i) dictionary.completion_count(random_string(5));

for (int i = 0; i < 10; ++i) dictionary.completions(random_string(5), results);

cout << "Assignment complete." << endl; }

//END MAIN.CPP

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NEED TO IMPLEMENT THIS FILE

//BEGIN AUTOCOMPLETER.CPP

//END AUTOCOMPLETER.CPP