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# include <iostream>
# include <cstdlib>
# include <fstream>
# include <string>
using namespace std;
struct node
{
int info;
struct node *left;
struct node *right;
}*root;
class BST
{
public:
void find(int, node **, node **);
void inOrderPrint(node *);
bool search(int);
void del(int);
bool insert(node*, int);
void case_a(node *,node *);
void case_b(node *,node *);
void case_c(node *,node *);
void display(node *, int);
void load_from_file(char *);
BST()
{
root = NULL;
}
};
int main()
{
int choice, num;
BST bst;
node *temp;
while (1)
{
cout<<" Binary Search Tree Menu "<<endl;
cout<<"=============================================="<<endl;
cout<<"1. Read values from a file to insert into tree"<<endl;
cout<<"2. Search the tree for a value" << endl;
cout<<"3. Delete Element "<<endl;
cout<<"4. Display"<<endl <<endl;
cout<<"0. Exit"<<endl <<endl;
cout<<"Enter your choice : " << endl;
cout<<"=============================================="<<endl;
cin>>choice;
switch(choice)
{
case 1:
char s[10];
cout << "What file do you want to read:hw3_ input1, hw3_input2, or hw3_input3? " << endl;
cin >> s;
bst.load_from_file(s);
break;
case 2:
if(root == NULL)
{
cout<<"Tree is empty, nothing to search"<< endl;
continue;
}
cout <<"Enter a number to be search: " << endl;
cin >> num;
bst.search(num);
if(root != NULL)
{
cout<<"FOUND"<<endl;
break;
}
else
{
cout<<"NOT FOUND"<<endl;
break;
}
break;
case 3:
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 4:
cout<<"Display BST:"<<endl;
bst.display(root,1);
//bst.inOrderPrint(root);
cout<<endl;
break;
case 0:
exit(1);
default:
cout<<"Error"<<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;
}
//Search Element from the tree
bool BST:: search(int item)
{
node *temp = temp;
while(temp!=NULL)
{
if(temp->info==item)
break;
if(item >temp->info)
temp = temp->right;
else
if(item < temp->info)
temp = temp->left;
}
if(temp ==NULL)
return false;
if(temp->info == item)
return true;
return false;
}
// Delete Element from the tree
void BST::del(int item)
{
node *parent, *root;
if (root == NULL)
{
cout<<"Tree empty"<<endl;
return;
}
find(item, &parent, &root);
if (root == NULL)
{
cout<<"Item not present in tree"<<endl;
return;
}
if (root->left == NULL && root->right == NULL)
case_a(parent, root);
if (root->left != NULL && root->right == NULL)
case_b(parent, root);
if (root->left == NULL && root->right != NULL)
case_b(parent, root);
if (root->left != NULL && root->right != NULL)
case_c(parent, root);
free(root);
}
/*
* 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;
}
// 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);
}
}
void BST::inOrderPrint(node * current)
{
if(current == NULL)
{
cout<<"Tree is empty"<< endl;
return;
}
//recursive call to the left and right
if(current != NULL)
{
inOrderPrint(current->left);
cout<<current->info<<" ";
inOrderPrint(current->right);
}
else
if(current == NULL)
return;
//check when we reach the bottom of the tree (left and right are NULL)
}
void BST::load_from_file(char * fn)
{
ifstream ifs;
ifs.open(fn);
if (ifs.is_open())
{
int num;
while (!ifs.eof())
{
ifs >> num;
if (ifs.good())
{
BST bst;
node *temp;
temp = new node;
temp->info = num;
bst.insert(root,num);
}
}
ifs.close();
}
}
bool BST::insert(node *tree, int info)
{
if(root == NULL){
root = new node;
root->info = info;
root->left = NULL;
root->right = NULL;
return true;
}
if(info > tree->info){
if(tree->right == NULL){
node * newnode;
newnode = new node;
newnode -> info = info;
newnode -> left = NULL;
newnode -> right = NULL;
return true;
}
return insert(tree->right, info);
}
if(info < tree->info){
if(tree->left == NULL){
node * newnode;
newnode = new node;
newnode->info = info;
newnode->right = NULL;
newnode->left = NULL;
return true;
}
return insert(tree->left, info);
}
return false;
}
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