Program to Determine Whether all Leaves are at Same Level

Program to Determine Whether all Leaves are at Same Level on fibonacci, factorial, prime, armstrong, swap, reverse, search, sort, stack, queue, array, linkedlist, tree, graph etc.

Q. Program to determine whether all leaves are at same level.

Explanation

In this program, we need to check whether all the leaves of the given binary tree are at same level or not.

A Node is said to be leaf if it doesn't have any child node. In the below diagram, nodes 4, 5 and 6 are leaf nodes as they don't have any child node. Nodes 4, 5 and 6 are present at the same level, i.e., Level 2.

Algorithm

1. Define Node class which has three attributes namely: data left and right. Here, left represents the left child of the node and right represents the right child of the node.
2. When a node is created, data will pass to data attribute of the node and both left and right will be set to null.
3. Define another class which has two attribute root and level.
1. Root represents the root node of the tree and initializes it to null.
2. The level will be used to store the level of the first encountered leaf node.
4. isSameLevel() will check whether all leaves of given binary tree are at same level or not:
1. It checks whether the root is null, which means the tree is empty.
2. If the tree is not empty, traverse through the tree and check for leaf node whose left and right children are null.
3. CurrentLevel will keep track of current level being traversed.
4. When the first leaf node is encountered, store the value of currentLevel in variable level.
5. Traverse recursively through all level, check for subsequent leaf nodes. If currentLevel of all leaf is equal to the value stored in level then, all leaves are at same level.

Python

```#Represent a node of binary tree
class Node:
def __init__(self,data):
#Assign data to the new node, set left and right children to None
self.data = data;
self.left = None;
self.right = None;

class LeafLevel:
def __init__(self):
#Represent the root of binary tree
self.root = None;
#It will store level of first encountered leaf
self.level = 0;

#isSameLevel() will check whether all leaves of the binary tree is at same level or not
def isSameLevel(self, temp, currentLevel):

#Check whether tree is empty
if(self.root == None):
print("Tree is empty");
return true;

else:
#Checks whether node is None
if(temp == None):
return True;

if(temp.left == None and temp.right == None):
#If first leaf is encountered, set level to current level
if(self.level == 0):
self.level = currentLevel;
return True;

#Checks whether the other leaves are at the same level as that of the first leaf
else:
return (self.level == currentLevel);

#Checks for leaf node in left and right subtree recursively.
return  (self.isSameLevel(temp.left, currentLevel + 1) and self.isSameLevel(temp.right, currentLevel + 1));

bt = LeafLevel();
#Add nodes to the binary tree
bt.root = Node(1);
bt.root.left = Node(2);
bt.root.right = Node(3);
bt.root.left.left = Node(4);
bt.root.right.left = Node(5);
bt.root.right.right = Node(6);

#Checks whether all leaves of given binary tree is at same level
if(bt.isSameLevel(bt.root, 1)):
print("All leaves are at same level");
else:
print("All leaves are not at same level");
```

Output:

```All leaves are at same level
```

C

```#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

//Represent a node of binary tree
struct node{
int data;
struct node *left;
struct node *right;
};

//Represent the root of binary tree
struct node *root = NULL;

//It will store level of first encountered leaf
static int level = 0;

//createNode() will create a new node
struct node* createNode(int data){
//Create a new node
struct node *newNode = (struct node*)malloc(sizeof(struct node));
//Assign data to newNode, set left and right children to NULL
newNode->data= data;
newNode->left = NULL;
newNode->right = NULL;

return newNode;
}

//isSameLevel() will check whether all leaves of the binary tree is at the same level or not
bool isSameLevel(struct node *temp, int currentLevel ) {

//Check whether tree is empty
if(root == NULL){
printf("Tree is empty\n");
return true;
}
else {
//Checks whether node is null
if(temp == NULL)
return true;

if(temp->left == NULL && temp->right == NULL) {
//If first leaf is encountered, set level to current level
if(level == 0) {
level = currentLevel ;
return true;
}
//Checks whether the other leaves are at the same level of that of first leaf
else
return (level == currentLevel) ;
}

//Checks for leaf node in left and right subtree recursively.
return  (isSameLevel(temp->left, currentLevel + 1) && isSameLevel(temp->right, currentLevel + 1)) ;
}
}

int main()
{
//Add nodes to the binary tree
root = createNode(1);
root->left = createNode(2);
root->right = createNode(3);
root->left->left = createNode(4);
root->right->left = createNode(5);
root->right->right = createNode(6);

//Checks whether all leaves of given binary tree is at same level
if(isSameLevel(root, 1))
printf("All leaves are at same level");
else
printf("All leaves are not at same level");

return 0;
}
```

Output:

```All leaves are at same level
```

JAVA

```public class LeafLevel {

//Represent a node of binary tree
public static class Node{
int data;
Node left;
Node right;

public Node(int data){
//Assign data to the new node, set left and right children to null
this.data = data;
this.left = null;
this.right = null;
}
}

//Represent the root of binary tree
public Node root;

//It will store level of first encountered leaf
public static int level = 0;

public LeafLevel(){
root = null;
}

//isSameLevel() will check whether all leaves of the binary tree is at same level or not
public boolean isSameLevel(Node temp, int currentLevel ) {

//Check whether tree is empty
if(root == null){
System.out.println("Tree is empty");
return true;
}
else {
//Checks whether node is null
if(temp==null)
return true;

if(temp.left == null && temp.right == null) {
//If first leaf is encountered, set level to current level
if(level == 0) {
level = currentLevel ;
return true;
}
//Checks whether the other leaves are at same level of that of first leaf
else
return (level == currentLevel) ;
}

//Checks for leaf node in left and right subtree recursively.
return  (isSameLevel(temp.left, currentLevel + 1) && isSameLevel(temp.right, currentLevel + 1)) ;
}
}

public static void main (String[] args) {

LeafLevel bt = new LeafLevel();
//Add nodes to the binary tree
bt.root = new Node(1);
bt.root.left = new Node(2);
bt.root.right = new Node(3);
bt.root.left.left = new Node(4);
bt.root.right.left = new Node(5);
bt.root.right.right = new Node(6);

//Checks whether all leaves of given binary tree is at same level
if(bt.isSameLevel(bt.root, 1))
System.out.println("All leaves are at same level");
else
System.out.println("All leaves are not at same level");
}
}
```

Output:

```All leaves are at same level
```

C#

```using System;
namespace Tree
{
public class Program
{
//Represent a node of binary tree
public class Node<T>{
public T data;
public Node<T> left;
public Node<T> right;

public Node(T data) {
//Assign data to the new node, set left and right children to null
this.data = data;
this.left = null;
this.right = null;
}
}

public class LeafLevel<T>{
//Represent the root of binary tree
public Node<T> root;

//It will store level of first encountered leaf
public static int level = 0;

public LeafLevel(){
root = null;
}

//isSameLevel() will check whether all leaves of the binary tree is at same level or not
public Boolean isSameLevel(Node<int> temp, int currentLevel ) {

//Check whether tree is empty
if(root == null){
Console.WriteLine("Tree is empty");
return true;
}
else {
//Checks whether node is null
if(temp==null)
return true;

if(temp.left == null && temp.right == null) {
//If first leaf is encountered, set level to current level
if(level == 0) {
level = currentLevel ;
return true;
}
//Checks whether the other leaves are at same level of that of first leaf
else
return (level == currentLevel) ;
}

//Checks for leaf node in left and right subtree recursively.
return  (isSameLevel(temp.left, currentLevel + 1) && isSameLevel(temp.right, currentLevel + 1)) ;
}
}
}

public static void Main()
{
LeafLevel<int> bt = new LeafLevel<int>();
//Add nodes to the binary tree
bt.root = new Node<int>(1);
bt.root.left = new Node<int>(2);
bt.root.right = new Node<int>(3);
bt.root.left.left = new Node<int>(4);
bt.root.right.left = new Node<int>(5);
bt.root.right.right = new Node<int>(6);

//Checks whether all leaves of given binary tree is at same level
if(bt.isSameLevel(bt.root, 1))
Console.WriteLine("All leaves are at same level");
else
Console.WriteLine("All leaves are not at same level");
}
}
}
```

Output:

```All leaves are at same level
```

PHP

```<!DOCTYPE html>
<html>
<body>
<?php
//Represent a node of binary tree
class Node{
public \$data;
public \$left;
public \$right;

function __construct(\$data){
//Assign data to the new node, set left and right children to NULL
\$this->data = \$data;
\$this->left = NULL;
\$this->right = NULL;
}
}
class LeafLevel{
//Represent the root of binary tree
public \$root;
//It will store level of first encountered leaf
public \$level = 0;

function __construct(){
\$this->root = NULL;
\$this->level = 0;
}

//isSameLevel() will check whether all leaves of the binary tree is at same level or not
function isSameLevel(\$temp, \$currentLevel ) {

//Check whether tree is empty
if(\$this->root == NULL){
print("Tree is empty <br>");
return true;
}
else {
//Checks whether node is null
if(\$temp == NULL)
return true;

if(\$temp->left == NULL && \$temp->right == NULL) {
//If first leaf is encountered, set level to current level
if(\$this->level == 0) {
\$this->level = \$currentLevel ;
return true;
}
//Checks whether the other leaves are at same level of that of first leaf
else
return (\$this->level == \$currentLevel) ;
}

//Checks for leaf node in left and right subtree recursively.
return  (\$this->isSameLevel(\$temp->left, \$currentLevel + 1) && \$this->isSameLevel(\$temp->right, \$currentLevel + 1)) ;
}
}
}
\$bt = new LeafLevel();
//Add nodes to the binary tree
\$bt->root= new Node(1);
\$bt->root->left = new Node(2);
\$bt->root->right = new Node(3);
\$bt->root->left->left = new Node(4);
\$bt->root->right->left = new Node(5);
\$bt->root->right->right = new Node(6);

//Checks whether all leaves of given binary tree is at same level
if(\$bt->isSameLevel(\$bt->root, 1))
print("All leaves are at same level");
else
print("All leaves are not at same level");
?>
</body>
</html>
```

Output:

```All leaves are at same level
```

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