C++ Program to Implement Binary Search Tree

This C++ Program demonstrates operations on Binary Search Tree

Here is source code of the C++ Program to demonstrate Binary Tree. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```
```
 * C++ Program To Implement BST
```
```
 */
```
```
# include <iostream>
```
```
# include <cstdlib>
```
```
using namespace std;
```
```
/*
```
```
 * Node Declaration
```
```
 */
```
```
struct node
```
```
{
```
```
    int info;
```
```
    struct node *left;
```
```
    struct node *right;
```
```
}*root;
```
```
 
```
```
/*
```
```
 * Class Declaration
```
```
 */
```
```
class BST
```
```
{
```
```
    public:
```

        void find(int, node **, node **);

```
        void insert(int);
```
```
        void del(int);
```
```
        void case_a(node *,node *);
```
```
        void case_b(node *,node *);
```
```
        void case_c(node *,node *);
```
```
        void preorder(node *);
```
```
        void inorder(node *);
```
```
        void postorder(node *);
```
```
        void display(node *, int);
```
```
        BST()
```
```
        {
```
```
            root = NULL;
```
```
        }
```
```
};
```
```
/*
```
```
 * Main Contains Menu
```
```
 */
```
```
int main()
```
```
{
```
```
    int choice, num;
```
```
    BST bst;
```
```
    node *temp;
```
```
    while (1)
```
```
    {
```

        cout<<"-----------------"<<endl;

        cout<<"Operations on BST"<<endl;

        cout<<"-----------------"<<endl;

        cout<<"1.Insert Element "<<endl;

        cout<<"2.Delete Element "<<endl;

        cout<<"3.Inorder Traversal"<<endl;

        cout<<"4.Preorder Traversal"<<endl;

        cout<<"5.Postorder Traversal"<<endl;

```
        cout<<"6.Display"<<endl;
```
```
        cout<<"7.Quit"<<endl;
```
```
        cout<<"Enter your choice : ";
```
```
        cin>>choice;
```
```
        switch(choice)
```
```
        {
```
```
        case 1:
```
```
            temp = new node;
```

            cout<<"Enter the number to be inserted : ";

```
	    cin>>temp->info;
```
```
            bst.insert(root, temp);
```
```
        case 2:
```
```
            if (root == NULL)
```
```
            {
```

                cout<<"Tree is empty, nothing to delete"<<endl;

```
                continue;
```
```
            }
```

            cout<<"Enter the number to be deleted : ";

```
            cin>>num;
```
```
            bst.del(num);
```
```
            break;
```
```
        case 3:
```

            cout<<"Inorder Traversal of BST:"<<endl;

```
            bst.inorder(root);
```
```
            cout<<endl;
```
```
            break;
```
```
	case 4:
```

            cout<<"Preorder Traversal of BST:"<<endl;

```
            bst.preorder(root);
```
```
            cout<<endl;
```
```
            break;
```
```
        case 5:
```

            cout<<"Postorder Traversal of BST:"<<endl;

```
            bst.postorder(root);
```
```
            cout<<endl;
```
```
            break;
```
```
        case 6:
```
```
            cout<<"Display BST:"<<endl;
```
```
            bst.display(root,1);
```
```
            cout<<endl;
```
```
            break;
```
```
        case 7:
```
```
            exit(1);
```
```
        default:
```
```
            cout<<"Wrong choice"<<endl;
```
```
        }
```
```
    }
```
```
}
```
```
 
```
```
/*
```
```
 * Find Element in the Tree
```
```
 */
```

void BST::find(int item, node **par, node **loc)

```
{
```
```
    node *ptr, *ptrsave;
```
```
    if (root == NULL)
```
```
    {
```
```
        *loc = NULL;
```
```
        *par = NULL;
```
```
        return;
```
```
    }
```
```
    if (item == root->info)
```
```
    {
```
```
        *loc = root;
```
```
        *par = NULL;
```
```
        return;
```
```
    }
```
```
    if (item < root->info)
```
```
        ptr = root->left;
```
```
    else
```
```
        ptr = root->right;
```
```
    ptrsave = root;
```
```
    while (ptr != NULL)
```
```
    {
```
```
        if (item == ptr->info)
```
```
        {
```
```
            *loc = ptr;
```
```
            *par = ptrsave;
```
```
            return;
```
```
        }
```
```
        ptrsave = ptr;
```
```
        if (item < ptr->info)
```
```
            ptr = ptr->left;
```
```
	else
```
```
	    ptr = ptr->right;
```
```
    }
```
```
    *loc = NULL;
```
```
    *par = ptrsave;
```
```
}
```
```
 
```
```
/*
```
```
 * Inserting Element into the Tree
```
```
 */
```

void BST::insert(node *tree, node *newnode)

```
{
```
```
    if (root == NULL)
```
```
    {
```
```
        root = new node;
```
```
        root->info = newnode->info;
```
```
        root->left = NULL;
```
```
        root->right = NULL;
```

        cout<<"Root Node is Added"<<endl;

```
        return;
```
```
    }
```
```
    if (tree->info == newnode->info)
```
```
    {
```

        cout<<"Element already in the tree"<<endl;

```
        return;
```
```
    }
```
```
    if (tree->info > newnode->info)
```
```
    {
```
```
        if (tree->left != NULL)
```
```
        {
```

            insert(tree->left, newnode);

```
	}
```
```
	else
```
```
	{
```
```
            tree->left = newnode;
```
```
            (tree->left)->left = NULL;
```
```
            (tree->left)->right = NULL;
```

            cout<<"Node Added To Left"<<endl;

```
            return;
```
```
        }
```
```
    }
```
```
    else
```
```
    {
```
```
        if (tree->right != NULL)
```
```
        {
```

            insert(tree->right, newnode);

```
        }
```
```
        else
```
```
        {
```
```
            tree->right = newnode;
```
```
            (tree->right)->left = NULL;
```

            (tree->right)->right = NULL;

            cout<<"Node Added To Right"<<endl;

```
            return;
```
```
        }	
```
```
    }
```
```
}
```
```
 
```
```
/*
```
```
 * Delete Element from the tree
```
```
 */
```
```
void BST::del(int item)
```
```
{
```
```
    node *parent, *location;
```
```
    if (root == NULL)
```
```
    {
```
```
        cout<<"Tree empty"<<endl;
```
```
        return;
```
```
    }
```
```
    find(item, &parent, &location);
```
```
    if (location == NULL)
```
```
    {
```

        cout<<"Item not present in tree"<<endl;

```
        return;
```
```
    }
```

    if (location->left == NULL && location->right == NULL)

```
        case_a(parent, location);
```

    if (location->left != NULL && location->right == NULL)

```
        case_b(parent, location);
```

    if (location->left == NULL && location->right != NULL)

```
        case_b(parent, location);
```

    if (location->left != NULL && location->right != NULL)

```
        case_c(parent, location);
```
```
    free(location);
```
```
}
```
```
 
```
```
/*
```
```
 * Case A
```
```
 */
```
```
void BST::case_a(node *par, node *loc )
```
```
{
```
```
    if (par == NULL)
```
```
    {
```
```
        root = NULL;
```
```
    }
```
```
    else
```
```
    {
```
```
        if (loc == par->left)
```
```
            par->left = NULL;
```
```
        else
```
```
            par->right = NULL;
```
```
    }
```
```
}
```
```
 
```
```
/*
```
```
 * Case B
```
```
 */
```
```
void BST::case_b(node *par, node *loc)
```
```
{
```
```
    node *child;
```
```
    if (loc->left != NULL)
```
```
        child = loc->left;
```
```
    else
```
```
        child = loc->right;
```
```
    if (par == NULL)
```
```
    {
```
```
        root = child;
```
```
    }
```
```
    else
```
```
    {
```
```
        if (loc == par->left)
```
```
            par->left = child;
```
```
        else
```
```
            par->right = child;
```
```
    }
```
```
}
```
```
 
```
```
/*
```
```
 * Case C
```
```
 */
```
```
void BST::case_c(node *par, node *loc)
```
```
{
```
```
    node *ptr, *ptrsave, *suc, *parsuc;
```
```
    ptrsave = loc;
```
```
    ptr = loc->right;
```
```
    while (ptr->left != NULL)
```
```
    {
```
```
        ptrsave = ptr;
```
```
        ptr = ptr->left;
```
```
    }
```
```
    suc = ptr;
```
```
    parsuc = ptrsave;
```

    if (suc->left == NULL && suc->right == NULL)

```
        case_a(parsuc, suc);
```
```
    else
```
```
        case_b(parsuc, suc);
```
```
    if (par == NULL)
```
```
    {
```
```
        root = suc;
```
```
    }
```
```
    else
```
```
    {
```
```
        if (loc == par->left)
```
```
            par->left = suc;
```
```
        else
```
```
            par->right = suc;
```
```
    }
```
```
    suc->left = loc->left;
```
```
    suc->right = loc->right;
```
```
}
```
```
 
```
```
/*
```
```
 * Pre Order Traversal
```
```
 */
```
```
void BST::preorder(node *ptr)
```
```
{
```
```
    if (root == NULL)
```
```
    {
```
```
        cout<<"Tree is empty"<<endl;
```
```
        return;
```
```
    }
```
```
    if (ptr != NULL)
```
```
    {
```
```
        cout<<ptr->info<<"  ";
```
```
        preorder(ptr->left);
```
```
        preorder(ptr->right);
```
```
    }
```
```
}
```
```
/*
```
```
 * In Order Traversal
```
```
 */
```
```
void BST::inorder(node *ptr)
```
```
{
```
```
    if (root == NULL)
```
```
    {
```
```
        cout<<"Tree is empty"<<endl;
```
```
        return;
```
```
    }
```
```
    if (ptr != NULL)
```
```
    {
```
```
        inorder(ptr->left);
```
```
        cout<<ptr->info<<"  ";
```
```
        inorder(ptr->right);
```
```
    }
```
```
}
```
```
 
```
```
/*
```
```
 * Postorder Traversal
```
```
 */
```
```
void BST::postorder(node *ptr)
```
```
{
```
```
    if (root == NULL)
```
```
    {
```
```
        cout<<"Tree is empty"<<endl;
```
```
        return;
```
```
    }
```
```
    if (ptr != NULL)
```
```
    {
```
```
        postorder(ptr->left);
```
```
        postorder(ptr->right);
```
```
        cout<<ptr->info<<"  ";
```
```
    }
```
```
}
```
```
 
```
```
/*
```
```
 * Display Tree Structure
```
```
 */
```
```
void BST::display(node *ptr, int level)
```
```
{
```
```
    int i;
```
```
    if (ptr != NULL)
```
```
    {
```
```
        display(ptr->right, level+1);
```
```
        cout<<endl;
```
```
        if (ptr == root)
```
```
            cout<<"Root->:  ";
```
```
        else
```
```
        {
```
```
            for (i = 0;i < level;i++)
```
```
                cout<<"       ";
```
```
	}
```
```
        cout<<ptr->info;
```
```
        display(ptr->left, level+1);
```
```
    }
```
```
}
```

$ g++ bst.cpp
$ a.out
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 8
Root Node is Added
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
Root->:  8
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 9
Node Added To Right
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
              9
Root->:  8
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 5
Node Added To Left
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
              9
Root->:  8
              5
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 11
Node Added To Right
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
                     11
              9
Root->:  8
              5
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 3 
Node Added To Left
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 7
Node Added To Right
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
                     11
              9
Root->:  8
                     7
              5
                     3
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 10
Node Added To Left
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
                     11
                            10
              9
Root->:  8
                     7
              5
                     3
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 2
Enter the number to be deleted : 10
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
                     11
              9
Root->:  8
                     7
              5
                     3
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 3
Inorder Traversal of BST:
3  5  7  8  9  11  
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 4
Preorder Traversal of BST:
8  5  3  7  9  11  
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 5
Postorder Traversal of BST:
3  7  5  11  9  8  
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 2
Enter the number to be deleted : 8
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
              11
Root->:  9
                     7
              5
                     3
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 10
Node Added To Left
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
              11
                     10
Root->:  9
                     7
              5
                     3
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 1
Enter the number to be inserted : 15
Node Added To Right
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
                     15
              11
                     10
Root->:  9
                     7
              5
                     3
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 4
Preorder Traversal of BST:
9  5  3  7  11  10  15  
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 5
Postorder Traversal of BST:
3  7  5  10  15  11  9  
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 6
Display BST:
 
                     15
              11
                     10
Root->:  9
                     7
              5
                     3
-----------------
Operations on BST
-----------------
1.Insert Element 
2.Delete Element 
3.Inorder Traversal
4.Preorder Traversal
5.Postorder Traversal
6.Display
7.Quit
Enter your choice : 7
 
 
------------------
(program exited with code: 1)
Press return to continue

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