Initial commit
This commit is contained in:
Michael Reber
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Binary Search Tree Program
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#include <iostream>
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#include <cstdlib>
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using namespace std;
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class BinarySearchTree
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{
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private:
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struct tree_node
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{
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tree_node* left;
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tree_node* right;
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int data;
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};
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tree_node* root;
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public:
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BinarySearchTree()
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{
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root = NULL;
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}
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bool isEmpty() const { return root==NULL; }
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void print_inorder();
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void inorder(tree_node*);
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void print_preorder();
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void preorder(tree_node*);
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void print_postorder();
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void postorder(tree_node*);
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void insert(int);
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void remove(int);
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};
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// Smaller elements go left
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// larger elements go right
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void BinarySearchTree::insert(int d)
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{
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tree_node* t = new tree_node;
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tree_node* parent;
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t->data = d;
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t->left = NULL;
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t->right = NULL;
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parent = NULL;
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// is this a new tree?
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if(isEmpty()) root = t;
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else
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{
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//Note: ALL insertions are as leaf nodes
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tree_node* curr;
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curr = root;
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// Find the Node's parent
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while(curr)
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{
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parent = curr;
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if(t->data > curr->data) curr = curr->right;
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else curr = curr->left;
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}
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if(t->data < parent->data)
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parent->left = t;
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else
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parent->right = t;
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}
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}
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void BinarySearchTree::remove(int d)
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{
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//Locate the element
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bool found = false;
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if(isEmpty())
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{
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cout<<" This Tree is empty! "<<endl;
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return;
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}
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tree_node* curr;
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tree_node* parent;
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curr = root;
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while(curr != NULL)
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{
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if(curr->data == d)
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{
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found = true;
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break;
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}
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else
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{
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parent = curr;
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if(d>curr->data) curr = curr->right;
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else curr = curr->left;
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}
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}
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if(!found)
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{
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cout<<" Data not found! "<<endl;
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return;
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}
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// 3 cases :
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// 1. We're removing a leaf node
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// 2. We're removing a node with a single child
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// 3. we're removing a node with 2 children
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// Node with single child
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if((curr->left == NULL && curr->right != NULL)|| (curr->left != NULL
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&& curr->right == NULL))
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{
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if(curr->left == NULL && curr->right != NULL)
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{
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if(parent->left == curr)
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{
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parent->left = curr->right;
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delete curr;
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}
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else
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{
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parent->right = curr->right;
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delete curr;
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}
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}
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else // left child present, no right child
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{
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if(parent->left == curr)
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{
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parent->left = curr->left;
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delete curr;
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}
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else
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{
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parent->right = curr->left;
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delete curr;
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}
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}
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return;
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}
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//We're looking at a leaf node
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if( curr->left == NULL && curr->right == NULL)
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{
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if(parent->left == curr) parent->left = NULL;
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else parent->right = NULL;
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delete curr;
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return;
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}
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//Node with 2 children
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// replace node with smallest value in right subtree
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if (curr->left != NULL && curr->right != NULL)
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{
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tree_node* chkr;
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chkr = curr->right;
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if((chkr->left == NULL) && (chkr->right == NULL))
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{
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curr = chkr;
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delete chkr;
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curr->right = NULL;
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}
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else // right child has children
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{
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//if the node's right child has a left child
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// Move all the way down left to locate smallest element
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if((curr->right)->left != NULL)
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{
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tree_node* lcurr;
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tree_node* lcurrp;
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lcurrp = curr->right;
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lcurr = (curr->right)->left;
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while(lcurr->left != NULL)
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{
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lcurrp = lcurr;
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lcurr = lcurr->left;
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}
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curr->data = lcurr->data;
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delete lcurr;
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lcurrp->left = NULL;
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}
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else
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{
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tree_node* tmp;
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tmp = curr->right;
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curr->data = tmp->data;
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curr->right = tmp->right;
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delete tmp;
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}
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}
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return;
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}
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}
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void BinarySearchTree::print_inorder()
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{
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inorder(root);
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}
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void BinarySearchTree::inorder(tree_node* p)
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{
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if(p != NULL)
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{
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if(p->left) inorder(p->left);
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cout<<" "<<p->data<<" ";
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if(p->right) inorder(p->right);
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}
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else return;
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}
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void BinarySearchTree::print_preorder()
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{
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preorder(root);
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}
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void BinarySearchTree::preorder(tree_node* p)
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{
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if(p != NULL)
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{
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cout<<" "<<p->data<<" ";
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if(p->left) preorder(p->left);
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if(p->right) preorder(p->right);
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}
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else return;
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}
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void BinarySearchTree::print_postorder()
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{
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postorder(root);
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}
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void BinarySearchTree::postorder(tree_node* p)
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{
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if(p != NULL)
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{
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if(p->left) postorder(p->left);
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if(p->right) postorder(p->right);
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cout<<" "<<p->data<<" ";
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}
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else return;
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}
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int main()
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{
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BinarySearchTree b;
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int ch,tmp,tmp1;
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while(1)
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{
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cout<<endl<<endl;
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cout<<" Binary Search Tree Operations "<<endl;
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cout<<" ----------------------------- "<<endl;
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cout<<" 1. Insertion/Creation "<<endl;
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cout<<" 2. In-Order Traversal "<<endl;
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cout<<" 3. Pre-Order Traversal "<<endl;
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cout<<" 4. Post-Order Traversal "<<endl;
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cout<<" 5. Removal "<<endl;
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cout<<" 6. Exit "<<endl;
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cout<<" Enter your choice : ";
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cin>>ch;
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switch(ch)
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{
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case 1 : cout<<" Enter Number to be inserted : ";
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cin>>tmp;
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b.insert(tmp);
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break;
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case 2 : cout<<endl;
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cout<<" In-Order Traversal "<<endl;
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cout<<" -------------------"<<endl;
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b.print_inorder();
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break;
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case 3 : cout<<endl;
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cout<<" Pre-Order Traversal "<<endl;
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cout<<" -------------------"<<endl;
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b.print_preorder();
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break;
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case 4 : cout<<endl;
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cout<<" Post-Order Traversal "<<endl;
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cout<<" --------------------"<<endl;
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b.print_postorder();
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break;
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case 5 : cout<<" Enter data to be deleted : ";
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cin>>tmp1;
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b.remove(tmp1);
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break;
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case 6 : system("pause");
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return 0;
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break;
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}
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}
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}
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