Question

C++ (Using Binary Search Trees)

other methods will result in downvote

Implement the binary search tree methods (bst.cpp) for the binary search tree provided in the header file. Test your implementation with the included test.

bst.h

bst_test.cpp

Note: Your implementation must correspond to declarations in the header file, and pass the test. Do not modify these two. I will compile your code against these. If the compilation fails, you will get down vote.

bst.h

#ifndef BINARY_SEARCH_TREE_H

#define BINARY_SEARCH_TREE_H

#include <string>

using namespace std;

class Node

{

private:

int key;

string val;

Node* left;

Node* right;

friend class BinarySearchTree;

};

class BinarySearchTree

{

public:

BinarySearchTree();

void insert(int key, string val); // Recursive

void printInOrder() const; // Prints keys in-order. Recursive

string find(int key) const; //Returns value if node is present, else return

empty string. Iterative

private:

Node* root;

void insertHelper(Node* parent, Node* new_node);

void printInOrderHelper(Node *n) const; //Helper for recursive

implemenation of printInroder()

};

#endif

bst_test.cpp

#include <iostream>

#include "bst.h"

using namespace std;

// Tests the binary search tree class.

int main()

{

BinarySearchTree t;

t.insert(5, "Boron");

t.insert(3, "Lithium");

t.insert(7, "Nitrogen");

t.insert(2, "Helium");

t.insert(4, "Berylium");

t.insert(6, "Carbon");

t.insert(8, "Oxygen");

t.printInOrder(); // Prints the keys in order (will appear sorted)

int ele = 8;

string val = t.find(ele);

if (val == "" ) {

cout << ele << " does not exist in tree" << endl;

} else {

cout << ele << " : " << val << endl;

}

ele = 0;

val = t.find(ele);

if (val == "" ) {

cout << ele << " does not exist in tree" << endl;

} else {

cout << ele << " : " << val << endl;

}

return 0;

}

Answer 1

//bst.h

#ifndef BINARY_SEARCH_TREE_H

#define BINARY_SEARCH_TREE_H

#include <string>

using namespace std;

class Node

{

private:

int key;

string val;

Node* left;

Node* right;

friend class BinarySearchTree;

};

class BinarySearchTree

{

public:

BinarySearchTree();

void insert(int key, string val); // Recursive

void printInOrder() const; // Prints keys in-order. Recursive

string find(int key) const; //Returns value if node is present, else return empty string. Iterative

private:

Node* root;

Node* insertHelper(Node* parent, Node* new_node);

void printInOrderHelper(Node *n) const; //Helper for recursive implemenation of printInroder()

};

#endif

//bst.cpp

#include"bst.h"
#include<iostream>
using namespace std;
BinarySearchTree::BinarySearchTree(){
   root = NULL;
}

void BinarySearchTree::insert(int key, string val){
   Node *newNode = new Node;
   newNode->key = key;
   newNode->val = val;
   newNode->left = NULL;
   newNode->right = NULL;
  
   root=insertHelper(root, newNode);
}

void BinarySearchTree::printInOrder() const{
   printInOrderHelper(root);
   cout<<endl;
} // Prints keys in-order. Recursive

string BinarySearchTree::find(int key) const{
   Node *head = root;
   while (head != NULL) {
// pass right subtree as new tree
if (key > head->key)
head = head->right;
  
// pass left subtree as new tree
else if (key < head->key)
head = head->left;
else
return head->val; // if the key is found return val
}
return "";
}

Node* BinarySearchTree::insertHelper(Node* parent, Node* new_node){
   if (parent == NULL) return new_node;

if (new_node->key < parent->key)
parent->left = insertHelper(parent->left, new_node);
else if (new_node->key > parent->key)
parent->right = insertHelper(parent->right, new_node);   

return parent;

}

void BinarySearchTree::printInOrderHelper(Node *n) const{
   if(n==NULL)return;
   printInOrderHelper(n->left);
   cout<<n->key<<" ";
   printInOrderHelper(n->right);
}

//bst_test.cpp

#include <iostream>

#include "bst.cpp"

using namespace std;

// Tests the binary search tree class.

int main()

{

BinarySearchTree t;

t.insert(5, "Boron");

t.insert(3, "Lithium");

t.insert(7, "Nitrogen");

t.insert(2, "Helium");

t.insert(4, "Berylium");

t.insert(6, "Carbon");

t.insert(8, "Oxygen");

t.printInOrder(); // Prints the keys in order (will appear sorted)

int ele = 8;

string val = t.find(ele);

if (val == "" ) {

cout << ele << " does not exist in tree" << endl;

} else {

cout << ele << " : " << val << endl;

}

ele = 0;

val = t.find(ele);

if (val == "" ) {

cout << ele << " does not exist in tree" << endl;

} else {

cout << ele << " : " << val << endl;

}

return 0;

}

//sample output