Computer Science Assignment 4 Solution

Exercise 1: Binary trees




Let consider the following template of binary trees




template <typename T




class BinaryTree{




private:




Declare a structure for the list struct TreeNode



{




T value;




struct TreeNode *left; struct TreeNode *right;




};










A function to create a node TreeNode * createNode(T key){



TreeNode *node = new TreeNode; node-value = key;




node-left = NULL; node-right = NULL; return node;




}




public:




BinaryTree (void) // Constructor




{ root = NULL; }










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BinaryTree (T);




BinaryTree (void); // Destructor T& top();



T& pop_front(); bool empty(); void insertNode(T);




void deleteNode(T, bool); void preOrderTraversal(); void inOrderTraversal(); void postOrderTraversal(); int countLesserThan(T); int countGreaterThan(T); int length();




int height(); void clear(); void mirror();




bool isIdenticalTo(BinaryTree); bool isIsomorphicWith(BinaryTree); int countLeafNodes();

int countSemiLeafNodes();




};




Suppose that this class permits the manipulation of binary search trees. Write an algorithm (Pseudo-code please, no sentences!!) and a C++ program for each of the following methods for this BinaryTree class:




BinaryTree(T info): the constructor to create a binary tree which first node contains the value info and the next pointer is null.
Hint: use the function TreeNode * createNode(T key);




~ BinaryTree (): a destructor that remove all elements of binary tree.



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T& top(): to get the first element of the binary tree.



T& pop_front(): to remove the first node of the binary tree and to return its value.



bool empty(): to test if the binary tree is empty or no.



void insertNode(T info): to insert a node in the binary tree.



void deleteNode(T info, bool removeAll): to delete a node the binary tree, if removeAll is true, all occurrence of info will be removed, otherwise, only the first occurrence of info will be removed.



void preOrderTraversal(): to display the binary tree using pre-order traversal.



void inOrderTraversal(): to display the binary tree using in-order traversal.



void postOrderTraversal(): to display the binary tree using post-order traversal.



int countLesserThan(T val): to count the the nodes which value is lesser than val in the binary tree.



int countGreaterThan(T val): to count the the nodes which value is greater than val in the binary tree.



int length(): to count the number of nodes in the binary tree.



int height(): to compute the height of the the binary tree.



void clear(): to remove all elements of the binary tree.



void mirror():swaps the left and right pointers of the tree. Below trees provide an



example input and output for mirror().






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4


/ \
/ \
2
5
5
2
/ \


/ \
1
3
3
1
INPUT TREE
OUTPUT TREE



bool isIdenticalTo(BinaryTree B): determines if the current binary tree is identical to the binary tree B.
bool isIsomorphicWith (BinaryTree ): determines if the current binary tree is isomorphic with the binary tree B. A binary tree is said to be isomorphic to , if its mirror is identical to the binary tree B.



bool countLeafNodes (): Counts the number of leaf nodes the binary tree.



bool countSemiLeafNodes (): Counts the number of semi-leaf nodes in the binary tree.



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Hint: some method can reuse other methods, like for example you can reuse the method clear() in the destructor.




Exercise 2: Binary min-heap




We saw in class that a binary min-heap can be represented by an array as illustrated in the figure 1.




















































Figure 1




For a given entry , it follows that the parent node is at /2, the left child is at the index 2k and the right child it at the index 2 + 1 as shown in the figure 2.

























Figure 2




The aim is to implement a class in C++ that manipulate the binary min-heap. For that purpose, let the following template of the binary min-heap:




template <typename T




class BinaryMinHeap{




private:




T *array; // An array to store the binary min-heap int capacity; // the capacity of this array int size; // the current size of this array




public:




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BinaryMinHeap (void)




{ array = NULL;




capacity = 0;




size = 0;




// Constructor



}




BinaryMinHeap (int Capacity);




BinaryMinHeap (void); // Destructor void precolate(int nodeI);



T getMin();




T extractMin();




void deleteNode(int nodeI);




void decreaseKey(int node, int new_val); void insertKey(T val);




T getLeftChild(int nodeI); T getRightChild(int nodeI); bool empty():

};




A utility function to swap two elements void swap(int *x, int *y) {



int temp = *x; *x = *y;

*y = temp;




}




Write an algorithm (Pseudo-code please, no sentences!!) and a C++ program for each of the following methods for this BinaryMinHeap class:




BinaryMinHeap (int Capacity): the constructor to create a binary min-heap with a capacity.



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~ BinaryMinHeap (): a destructor that remove all elements of the binary min-heap.



void percolate(int nodeI): to heapify a subtree with the root at given index.



T getMin(): gets the minimum value of the binary min-heap.



bool empty(): tests if the binary min-heap is empty or no.



T extractMin(): removes minimum element (or root) from the binary min-heap.



void deleteNode(int nodeI): deletes key at index i. (Hint: reduce the value associated to the key nodeI to minus infinite by using the function decreaseKey, then calls extractMin())
void insertKey(T val): inserts a new node which key is val.



T getLeftChild(int nodeI): gets the left child of nodeI.



T getRightChild(int nodeI): gets the right child of nodeI.



























































































































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