binaryTree_2.cpp

#include <iostream>
#include <queue>
using namespace std;

template <typename T>


class BinaryTreeNode
{
public:
    T data;
    BinaryTreeNode* left;
    BinaryTreeNode* right;

    BinaryTreeNode(T data){
        this->data=data;
        left=NULL;
        right=NULL;
    }

    ~BinaryTreeNode(){
        delete left;
        delete right;
    }
};

//printing binary tree
void printTree(BinaryTreeNode<int>* root)
{
    if(root==NULL)
        return;
    cout<<root->data<<":";
    if(root->left){
        cout<<"L"<<root->left->data<<" ";
    }
    if(root->right){
        cout<<"R"<<root->right->data<<" ";
    }
    cout<<endl;
    printTree(root->left);
    printTree(root->right);
}

//taking input
BinaryTreeNode<int>* takeInput(){
    int rootData;
    cout<<"Enter root data"<<endl;
    cin>>rootData;
    if(rootData==-1) return NULL;

    BinaryTreeNode<int>* root=new BinaryTreeNode<int>(rootData);
    BinaryTreeNode<int>* leftChild=takeInput();
    BinaryTreeNode<int>* rightChild=takeInput();
    root->left=leftChild;
    root->right=rightChild;
    return root;
}

//taking input level wise
BinaryTreeNode<int>* takeInputLevelwise(){
    int rootData;
    cout<<"Enter root data"<<endl;
    cin>>rootData;
    if(rootData==-1) return NULL;

    BinaryTreeNode<int>* root = new BinaryTreeNode<int>(rootData);
    queue<BinaryTreeNode<int>*> pendingNodes;
    pendingNodes.push(root);

    while(pendingNodes.size() != 0){
        BinaryTreeNode<int>* front = pendingNodes.front();
        pendingNodes.pop();

        cout<<"Enter left child of "<<front->data<<endl;
        int leftChildData;
        cin>>leftChildData;
        if(leftChildData!=-1){
            BinaryTreeNode<int>* child = new BinaryTreeNode<int>(leftChildData);
            front->left=child;
            pendingNodes.push(child);
        }

        cout<<"Enter right child of "<<front->data<<endl;
        int rightChildData;
        cin>>rightChildData;
        if(rightChildData!=-1){
            BinaryTreeNode<int>* child = new BinaryTreeNode<int>(rightChildData);
            front->right=child;
            pendingNodes.push(child);
        }
    }
    return root;

}

//counting nodes
int numNodes(BinaryTreeNode<int>* root){
    if(root==NULL)
        return 0;
    return 1+numNodes(root->left)+numNodes(root->right);
};

// 1 2 3 4 5 6 7 -1 -1 -1 -1 8 9 -1 -1 -1 -1 -1 -1
int main()
{
    //normal input
    //BinaryTreeNode<int>* root=takeInput();

    //levelwise input
    BinaryTreeNode<int>* root=takeInputLevelwise();
    cout<<"Total number of nodes: "<<numNodes(root)<<endl;
    printTree(root);
    delete root;
    return 0;
}