Printing Certain Elements In a Tree - c++

Question

I am required to make a program that will accept numbers from the user, the numbers are interpreted as a rating, for a game. The point of this program is to accept the numbers and make uneven teams in quality not quantity.
For example:
The user enters the numbers: 25, 50, 63, 80.
The bad team would be: 25, 50.
The good team would be: 63, 90.
I am using a binary search tree so the time is O(nlogn).
My code so far accepts numbers, puts them into a tree, determines if the teams are equal in numbers, but does not print them properly. I suspect the problem is either in my int main() when I call the print function or the actual print function.
#include <iostream>
using namespace std;
struct node
{
int data;
node *left;
node *right;
};
node *createNode(int data) // creates nodes
{
node *newNode = NULL;
newNode = new node;
newNode->data=data;
newNode->left=NULL;
newNode->right=NULL;
return newNode;
}
node *insert(int data, node **tree) // inserts them into a tree
{
node *newNode=NULL;
if (*tree==NULL)
{
newNode = createNode(data);
*tree = newNode;
}
else if (data<(*tree)->data)
{
if ((*tree)->left==NULL)
{
newNode = createNode(data);
(*tree)->left=newNode;
}
else
{
newNode = insert(data, &((*tree)->left));
}
}
else
{
if ((*tree)->right==NULL)
{
newNode = createNode(data);
(*tree)->right = newNode;
}
else
newNode = insert(data, &((*tree)->right));
}
return newNode;
}
void destroy(node *tree) // destroy tree at the end
{
if (tree!=NULL)
{
if (tree->left!=NULL)
destroy(tree->left);
if (tree->right!=NULL)
destroy(tree->right);
delete tree;
}
}
int treeHeight(node *tree, int counter) // finds the height of the tree
{
if (tree==NULL) // if there is nothing in the tree, return 0
return counter;
int leftcount, rightcount; // leftcount counts the left side of the tree and right count counts the right side of the tree
counter++; // counter should go up by 1 for every node
rightcount = treeHeight(tree->right, counter); // searches the right side
leftcount = treeHeight(tree->left, counter); // searches the left side
if (rightcount > leftcount) // return the height
return rightcount;
else
return leftcount;
}
void printNode(node *Node)
{
if (Node!=NULL)
{
cout << Node->data << ", ";
}
}
void printLeft(node *tree)
{
if (tree!=NULL)
{
printLeft(tree->left);
printNode(tree);
}
}
void printRight(node *tree)
{
if (tree!=NULL)
{
printRight(tree->right);
printNode(tree);
}
}
int main()
{
node *root = NULL;
node *current = NULL;
int value;
while (true)
{
cout << "Enter a rating where the bigger the number, the better (zero to quit): ";
cin >> value;
if (value==0)
break;
current = insert(value, &root);
}
int height = treeHeight(root, 0); // call the function and display the height of the tree
if (height==0)
{
cout << "\nYou did not enter any players, the game cannot happen now. Thanks a lot." << endl;
return 0;
}
else if (height%2!=0)
{
cout << "Uneven amount of player, add one more player to make the teams equal in quantity" << endl;
cout << "Enter a rating: ";
cin >> value;
current = insert(value, &root);
}
cout << "\nThe bad team is: " ;
printLeft(root); // ???
cout << "\nThe good team is: ";
printRight(root); // ???
destroy(root);
return 0;
}

Answer 1

Firstly, you must have misunderstood something. Binary Search Tree with this input: 25, 50, 63, 80 would not be divided in a way you wrote. Look. it would be constructed like that:
25
\
50
\
63
\
80
Not like that:
25
/ \
50 63
\
80
And not like that
50
/ \
25 63
\
80
I would advise you to go and simulate insertions to BST: BST simulator online
Now, about your code. Functions printLeft and printRight print only elements from left-most and right-most branch of the tree (and printLeft do it top-bottom while printRight do it bottom-top). That's why they give results 25 and 80, 63, 50, 25. I don't know exactly what your BST should be divided into "bad" and "good" team, but let's suppose that "bad" team consists of root node and left subtree thile "good" team consists of only right subtree (wihtour root node). Then you could use this function:
void printSubTree(node *tree) {
if (tree) {
printSubTree(tree->left);
printNode(tree);
printSubTree(tree->right);
}
}
And modify your code to:
if (root) {
cout << "\nThe bad team is: " ;
printNode(root);
printSubTree(root->left);
cout << "\nThe good team is: ";
printSubTree(root->right);
}