how to reset the pointer in BST? - c++

Question

I am trying to implement a Binary search tree with functionalities such as Deleting a node, finding the minimum node, maximum node, etc. But I am not able to Delete a node nor find Maximum or Minimum value in the tree. My take is that when I am inserting the nodes, the pointer to the node references to the last node hence my program cannot iterate from the root node. Any suggestion?
#include<iostream>
using namespace std;
struct BstNode
{
BstNode* left;
BstNode* right;
int data;
};
BstNode* GetnewNode(int data)
{
BstNode* newNode=new BstNode();
newNode->data=data;
newNode->left=NULL;
newNode->right=NULL;
return newNode;
}
BstNode* Insert(BstNode* root ,int data)
{
if(root==NULL)
{
root=GetnewNode(data);
}
else if(data<=root->data)
{
root=Insert(root->left,data);
}
else
{
root=Insert(root->right,data);
}
return root;
}
bool Search(BstNode* root, int data)
{
if(root==NULL)
{
return false;
}
else if(data==root->data)
{
return true;
}
else if(data<=root->data)
{
return Search(root->left,data);
}
else
{
return Search(root->right,data);
}
}
int FindMin(BstNode* root)
{
if(root==NULL)
{
return -1;
}
else
{
while(root->left!=NULL)
{
root=root->left;
}
}
return root->data;
}
bool IsBstUtil(BstNode* root, int minvalue, int maxvalue)
{
if(root==NULL)
return true;
if(root->data<minvalue && root->data >maxvalue && IsBstUtil(root->left,minvalue,root->data) && IsBstUtil(root->right,root->data,maxvalue))
{
return true;
}
else
{
return false;
}
}
bool IsBinarySearchTree(BstNode* root)
{
return IsBstUtil(root, INT_MIN, INT_MAX);
}
int FindMax(BstNode* root)
{
if(root==NULL)
{
return -1;
}
else
{
while(root->right!=NULL)
{
root=root->right;
}
}
return root->data;
}
BstNode* del(BstNode* root, int data)
{
if(root==NULL)
return root;
else if(data<=root->data)
root->left=del(root->left,data);
else if(data>root->data)
root->right=del(root->right,data);
else
{
if(root->left==NULL && root->right==NULL)
{
root=NULL;
delete root;
}
else if(root->left==NULL)
{
BstNode* temp=root;
root=root->right;
delete temp;
return root;
}
else if(root->right==NULL)
{
BstNode* temp=root;
root=root->left;
delete temp;
return root;
}
}
}
int main()
{
BstNode* root=NULL;
root=Insert(root,1);
root=Insert(root,3);
root=Insert(root,4);
}

Answer 1

Just instead of doing root = Insert(root->left,data); you should do set it as left to the root i.e
root->left = Insert(root->left,data);
Insert function:
BstNode* Insert(BstNode* root ,int data)
{
if(root==NULL)
{
root=GetnewNode(data);
}
else if(data<=root->data)
{
// setting the left to root
root->left=Insert(root->left,data);
}
else
{
// setting the right to root
root->right=Insert(root->right,data);
}
// returning the root itself
return root;
}