BinarySearchTree.cpp

#include <iostream>
class BinTreeNode
{
public:
    BinTreeNode(int value)
    {
        this->value = value;
        this->left = NULL;
        this->right = NULL;
    }
    int value;
    BinTreeNode* left;
    BinTreeNode* right;
};
BinTreeNode* tree_insert(BinTreeNode* tree, int item)
{
    if (tree == NULL)
        tree = new BinTreeNode(item);
    else if (item < tree->value)
        if (tree->left == NULL)
            tree->left = new BinTreeNode(item);
        else
            tree_insert(tree->left, item);
    else if (tree->right == NULL)
        tree->right = new BinTreeNode(item);
    else
        tree_insert(tree->right, item);
    return tree;
}
void postorder(BinTreeNode* tree)
{
    if (tree->left != NULL)
        postorder(tree->left);
    if (tree->right != NULL)
        postorder(tree->right);
    std::cout << tree->value << std::endl;
}
void in_order(BinTreeNode* tree)
{
    if (tree->left != NULL)
        in_order(tree->left);
    std::cout << tree->value << std::endl;
    if (tree->right != NULL)
        in_order(tree->right);
}
BinTreeNode* FindMin(BinTreeNode* tree)
{
    if(tree == NULL)
    {
        std::cout<<"Error: Tree is empty\n";
    }
    while(tree->left != NULL)
    {
        tree = tree->left;
    }
    return tree;
}
BinTreeNode* tree_delete(BinTreeNode* tree, int item)
{
    if(tree==NULL) return tree;
    else if(item < tree->value)
        tree->left=tree_delete(tree->left,item);
    else if(item > tree->value)
        tree->right=tree_delete(tree->right,item);
    else
    {
        if(tree->left == NULL && tree->right == NULL)
        {
            delete tree;
            tree = NULL;
            return tree;
        }
        else if(tree->left == NULL)
        {
            BinTreeNode* temp= tree;
            tree = tree->right;
            delete temp;
            return tree;
        }
        else if(tree->right == NULL)
        {
            BinTreeNode* temp= tree;
            tree = tree->left;
            delete temp;
            return tree;
        }
        else
        {
            BinTreeNode* temp = FindMin(tree->right);
            tree->value = temp->value;
            tree->right=tree_delete(tree->right,temp->value);
        }
    }
    return tree;
}
int main(int argc, char *argv[])
{
    BinTreeNode* t = tree_insert(0, 6);
    tree_insert(t, 10);
    tree_insert(t, 5);
    tree_insert(t, 2);
    tree_insert(t, 3);
    tree_insert(t, 4);
    tree_insert(t, 11);
    in_order(t);
    tree_delete(t,2);
    in_order(t);
    tree_delete(t,6);
    in_order(t);
    return 0;
}