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Binary_trees.cpp
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Binary_trees.cpp
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//*************************************************BINARY TREES*****
#include<iostream>
#include<queue>
using namespace std;
//1)Create a Binary Tree node class
template <typename T>
class BinaryTreeNode{
public:
T data;
BinaryTreeNode* left;
BinaryTreeNode* right;
//constructor to initialize the binary search tree
BinaryTreeNode(T data) {
this->data=data;
left=NULL;
right=NULL;
}
//Destructor to delete the complete binary tree
~BinaryTreeNode(){
delete left;
delete right;
}
};
//2)Function to take input of binary tree from the user levelwise
BinaryTreeNode<int>* takeinput(){
int rootdata;
cout<<"Enter root data: ";
cin>>rootdata;
if(rootdata==-1){
return NULL;
}
BinaryTreeNode<int>* root=new BinaryTreeNode<int>(rootdata);
queue<BinaryTreeNode<int>*> pendnodes;
pendnodes.push(root);
while(pendnodes.size()!=0){
BinaryTreeNode<int>* curr=pendnodes.front();
pendnodes.pop();
int leftchilddata,rightchilddata;
cout<<"Enter the left child of "<<curr->data<<": ";
cin>>leftchilddata;
if(leftchilddata!=-1){
BinaryTreeNode<int>* leftchild=new BinaryTreeNode<int>(leftchilddata);
curr->left=leftchild;
pendnodes.push(leftchild);
}
cout<<"Enter the right child of "<<curr->data<<": ";
cin>>rightchilddata;
if(rightchilddata!=-1){
BinaryTreeNode<int>* rightchild=new BinaryTreeNode<int>(rightchilddata);
curr->right=rightchild;
pendnodes.push(rightchild);
}
/* if(leftchilddata==-1 || rightchilddata==-1){
continue;
} */
}
return root;
}
//3)Function to print the Binary Tree //in recurssive manner i.e,not levelwise
void PrintBinaryTree(BinaryTreeNode<int>* root){
//Base case
if(root==NULL) return;
cout<<root->data<<": ";
if(root->left!=NULL) cout<<'L'<<root->left->data<<',';
if(root->right!=NULL) cout<<'R'<<root->right->data;
cout<<endl;
PrintBinaryTree(root->left);
PrintBinaryTree(root->right);
}
//Function to print Binary Tree levelwise (use queue)
void PrintBinaryTreeLevelWise(BinaryTreeNode<int>* root){
if(root==NULL){
return;
}
queue<BinaryTreeNode<int>*> pendingnodes;
pendingnodes.push(root);
while(!pendingnodes.empty()){
BinaryTreeNode<int>* curr=pendingnodes.front();
pendingnodes.pop();
cout<<curr->data<<": ";
if(curr->left!=NULL){
pendingnodes.push(curr->left);
cout<<'L'<<curr->left->data<<',';
}
if(curr->right!=NULL){
pendingnodes.push(curr->right);
cout<<'R'<<curr->right->data;
}
cout<<endl;
}
return;
}
//Function to count the numer of nodes in the Binatry Tree
int countnodes(BinaryTreeNode<int>* root){
if(root==NULL){
return 0;
}
return 1+countnodes(root->left) + countnodes(root->right);
}
/*Find a node
Given a Binary Tree and an integer x, check if node with data x is present in the input binary tree or not. Return true or false.
*/
bool isXpresent(BinaryTreeNode<int>* root,int x){
if(root==nullptr) return false;
if(root->data == x){
return true;
}
return (isXpresent(root->left, x) || isXpresent(root->right, x));
}
//Function to find the height of the binary tree
int height(BinaryTreeNode<int>* root){
if(root==NULL) return 0;
return 1+max(height(root->left),height(root->right));
}
//Mirror the given binary tree. That is, right child of every nodes
//should become left and left should become right.
BinaryTreeNode<int>* Mirrortree(BinaryTreeNode<int>* root){
if(root==NULL) return NULL;
if(root->left!=NULL && root->right!=NULL){
Mirrortree(root->left);
Mirrortree(root->right);
BinaryTreeNode<int>* temp=root->left;
root->left=root->right;
root->right=temp;
}
else if(root->left==NULL){
Mirrortree(root->right);
root->left=root->right;
root->right=NULL;
}
else if(root->right==NULL){
root->right=root->left;
root->left=NULL;
}
return root;
}
//Function for inorder printing i.e,(left->root, root, right->root)
void inorderprint(BinaryTreeNode<int>* root){
if(root==NULL) return;
inorderprint(root->left);
cout<<root->data<<" ";
inorderprint(root->right);
}
/*Preorder Binary Tree
Given a binary tree, print the preorder traversal of given tree.
Pre-order traversal is: Root LeftChild RightChild*/
void preorderprint(BinaryTreeNode<int>* root){
if(root==NULL) return;
cout<<root->data<<" ";
preorderprint(root->left);
preorderprint(root->right);
}
/*Postorder Binary Tree
Given a binary tree, print the postorder traversal of given tree.
Post-order traversal is: LeftChild RightChild Root
*/
void postorderprint(BinaryTreeNode<int>* root){
if(root==NULL) return;
postorderprint(root->left);
postorderprint(root->right);
cout<<root->data<<" ";
}
//Build tree helper function
BinaryTreeNode<int>* BuildTreeHelper(int *in,int* pre,int inS,int inE,int preS,int preE){
if(inS>inE){
return NULL;
}
int rootdata;
rootdata=pre[preS];
int rootindex=-1;
for(int i=inS;i<=inE;i++){
if(in[i]==rootdata){
rootindex=i;
break;
}
}
int linS=inS;
int linE=rootindex-1;
int lpreS=preS+1;
int lpreE=lpreS+linE-linS;
int rinS=rootindex+1;
int rinE=inE;
int rpreS=lpreE+1;
int rpreE=preE;
BinaryTreeNode<int>* root=new BinaryTreeNode<int>(rootdata);
root->left=BuildTreeHelper(in,pre,linS,linE,lpreS,lpreE);
root->right=BuildTreeHelper(in,pre,rinS,rinE,rpreS,rpreE);
return root;
}
//Given the inorder and the preorder.we need to build the binary tree and return the root
BinaryTreeNode<int>* Buildtree(int* in, int* pre, int n){
return BuildTreeHelper(in,pre,0,n-1,0,n-1);
}
//Another process
//Build a binary tree from postorder and inorder. We need to build the tree and return the root
BinaryTreeNode<int>* buildtreefrompostandinorder(int* pos,int possize,int* in,int insize){
//Base case
if(pos==NULL || in==NULL || possize==0 || possize!=insize){
return NULL;
}
int rootdata=pos[possize-1];
int leftcount=0,rightcount;
while(leftcount<insize && in[leftcount]!=rootdata){
leftcount++;
}
rightcount=insize-leftcount-1;
BinaryTreeNode<int>* root=new BinaryTreeNode<int>(rootdata);
root->left=buildtreefrompostandinorder(pos,leftcount,in,leftcount);
root->right=buildtreefrompostandinorder(pos+leftcount,rightcount,in+leftcount+1,rightcount);
return root;
}
//Function to find both the height and the diameter
//USE INBUILT PAIR FUNCTION
pair<int,int> findheightdiameter(BinaryTreeNode<int>* root){
pair<int,int> p;
if(root==NULL){
p.first=0;
p.second=0;
return p;
}
int height=0,diameter=0;
int leftheight = findheightdiameter(root->left).first;
int rightheight= findheightdiameter(root->right).first;
height= 1+max(leftheight,rightheight);
diameter= max(leftheight+rightheight, max(findheightdiameter(root->left).second,findheightdiameter(root->right).second));
p.first=height;
p.second=diameter;
return p;
}
//Function to find the maximum and minimum in the binary tree
pair<int,int> findminmax(BinaryTreeNode<int>* root){
pair<int,int> p;
if(root==NULL){
p.first=INT_MAX;
p.second=INT_MIN;
return p;
}
p.first=root->data;
p.second=root->data;
pair<int,int> leftminmax=findminmax(root->left);
pair<int,int> rightminmax=findminmax(root->right);
p.first=min(p.first,min(leftminmax.first,rightminmax.first));
p.second=max(p.second,max(leftminmax.second,rightminmax.second));
return p;
}
//Function to find the sum of all the nodes in the Binary Tree
int findsum(BinaryTreeNode<int>* root){
if(root==NULL){
return 0;
}
int sum=root->data;
return sum+findsum(root->left)+findsum(root->right);
}
//Function to check if the tree is balanced
pair<int,bool> isbalanced(BinaryTreeNode<int>* &root){
pair<int,bool> ans;
if(root==NULL){
ans.first=0;
ans.second=true;
return ans;
}
int height=0;
bool checkbalanced=true;
int leftheight=isbalanced(root->left).first;
int rightheight=isbalanced(root->right).first;
height=1+max(leftheight,rightheight);
if(isbalanced(root->left).second==true && isbalanced(root->right).second==true){
if(abs(leftheight-rightheight)<=1){
checkbalanced=true;
}
else checkbalanced=false;
}
else if(isbalanced(root->left).second==false || isbalanced(root->right).second==false){
checkbalanced=false;
}
ans.first=height;
ans.second=checkbalanced;
return ans;
}
//Function for level order Traversal
void Levelordertraversal(BinaryTreeNode<int>* &root){
if(root==NULL){
return;
}
queue<BinaryTreeNode<int>*> pendingnodes;
pendingnodes.push(root);
pendingnodes.push(NULL);
while(pendingnodes.size()>1){
BinaryTreeNode<int>* curr=pendingnodes.front();
pendingnodes.pop();
if(curr==NULL){
pendingnodes.push(NULL);
cout<<endl;
}
else{
if(curr->left)
pendingnodes.push(curr->left);
if(curr->right)
pendingnodes.push(curr->right);
cout<<curr->data<<" ";
}
}
return;
}
//Function for Zigzag Traversal
/*Given a binary tree, print the zig zag order i.e print level 1 from left to right
level 2 from right to left and so on. This means odd levels should get printed
from left to right and even level right to left.
*/
void Zigzagtraversal(BinaryTreeNode<int>* &root){
if(root==NULL){
return;
}
queue<BinaryTreeNode<int>*> pendingnodes;
pendingnodes.push(root);
pendingnodes.push(NULL);
int count=0;
while(pendingnodes.size()>1){
BinaryTreeNode<int>* curr=pendingnodes.front();
pendingnodes.pop();
if(curr==NULL){
pendingnodes.push(NULL);
cout<<endl;
count++;
}
else{
if(count%2!=0){
if(curr->left)
pendingnodes.push(curr->left);
if(curr->right)
pendingnodes.push(curr->right);
cout<<curr->data<<" ";
}
else{
if(curr->right)
pendingnodes.push(curr->right);
if(curr->left)
pendingnodes.push(curr->left);
cout<<curr->data<<" ";
}
}
}
return;
}
//Function to remove leaf nodes from the binary tree and return the root
BinaryTreeNode<int>* removeleafnode(BinaryTreeNode<int>* &root){
if(root==NULL) return NULL;
//Base case
if(root->left==NULL && root->right==NULL){
root=NULL;
return root;
}
removeleafnode(root->left);
removeleafnode(root->right);
return root;
}
/*Level wise linkedlist
Given a binary tree, write code to create a separate linked list for each level.
You need to return the array which contains head of each level linked list.
*/
template <typename T>
class node{
public:
T data;
node<T>* next;
node(T data){
this->data=data;
this->next=NULL;
}
};
//Function to print the linked list
void printLL(node<int>* &root){
node<int>* temp=root;
while(temp!=NULL){
cout<<temp->data<<" ";
temp=temp->next;
}
cout<<endl;
}
vector<node<int>*> Levelwiselinkedlist(BinaryTreeNode<int>* &root){
vector<node<int>*> res;
if(root==NULL) return res;
queue<BinaryTreeNode<int>*> q;
node<int>* head=NULL;
node<int>* tail=NULL;
q.push(root);
q.push(NULL);
while(q.size()>0){
BinaryTreeNode<int>* curr=q.front();
q.pop();
if(q.size()==0){
res.push_back(head);
break;
}
else if(curr==NULL){
res.push_back(head);
q.push(NULL);
head=NULL;
tail=NULL;
}
else if(curr!=NULL){
if(curr->left) q.push(curr->left);
if(curr->right) q.push(curr->right);
node<int>* newnode= new node<int>(curr->data);
if(head==NULL){
head=newnode;
tail=newnode;
}
else{
tail->next=newnode;
tail=tail->next;
}
}
}
return res;
}
//Driver function
int main(){
/*
BinaryTreeNode<int>* root=new BinaryTreeNode<int>(1);
BinaryTreeNode<int>* node1=new BinaryTreeNode<int>(2);
BinaryTreeNode<int>* node2=new BinaryTreeNode<int>(3);
root->left=node1;
root->right=node2;
*/
BinaryTreeNode<int>* root=takeinput();
PrintBinaryTreeLevelWise(root);
//cout<<countnodes(root)<<endl;
//cout<<isXpresent(root,4)<<endl;
//cout<<height(root)<<endl;
/*
BinaryTreeNode<int>* mirtree=Mirrortree(root);
PrintBinaryTreeLevelWise(mirtree);
*/
/*
inorderprint(root);
cout<<endl;
postorderprint(root);
To build a tree from inorder and preorder
*/
/*
int in[]={4,2,5,1,8,6,9,3,7};
int post[]={4,5,2,8,9,6,7,3,1};
BinaryTreeNode<int>* root =buildtreefrompostandinorder(post,9,in,9);
PrintBinaryTreeLevelWise(root);
*/
/*
cout<<endl;
pair<int,int> p=findheightdiameter(root);
cout<<"Height:"<<p.first<<" Diameter:"<<p.second<<endl;
*/
/*
pair<int,int> p=findminmax(root);
cout<<"Minimum:"<<p.first<<" Maximum:"<<p.second<<endl;
*/
// cout<<findsum(root)<<endl;
/* pair<int,bool> ans=isbalanced(root);
cout<<ans.first<<" "<<ans.second;
*/
//BinaryTreeNode<int>* ans=removeleafnode(root);
//Levelordertraversal(root);
//zigzagtraversal(root);
vector<node<int>*> res=Levelwiselinkedlist(root);
for(int i=0;i<res.size();i++){
printLL(res[i]);
}
delete root;
}