Given a binary tree and two nodes, the task is to check if the nodes are siblings of each other or not.
Two nodes are said to be siblings if they are present at the same level, and their parents are the same.
Examples:
Input :
1
/ \
2 3
/ \ / \
4 5 6 7
First node is 4 and Second node is 6.
Output : No, they are not siblings.
Input :
1
/ \
5 6
/ / \
7 3 4
First node is 3 and Second node is 4
Output : Yes
Approach: On observing carefully, it can be concluded that any node in a binary tree can have maximum of two child nodes. So, since the parent of two siblings must be same, so the idea is to simply traverse the tree and for every node check if the two given nodes are its children. If it is true for any node in the tree then print YES otherwise print NO.
Below is the implementation of the above approach:
// C++ program to check if two nodes are // siblings #include <bits/stdc++.h> using namespace std;
// Binary Tree Node struct Node {
int data;
Node *left, *right;
}; // Utility function to create a new node struct Node* newNode( int data)
{ struct Node* node = new Node;
node->data = data;
node->left = node->right = NULL;
return (node);
} // Function to find out if two nodes are siblings bool CheckIfNodesAreSiblings(Node* root, int data_one,
int data_two)
{ if (!root)
return false ;
// Compare the two given nodes with
// the childrens of current node
if (root->left && root->right) {
int left = root->left->data;
int right = root->right->data;
if (left == data_one && right == data_two)
return true ;
else if (left == data_two && right == data_one)
return true ;
}
// Check for left subtree
if (root->left)
if (CheckIfNodesAreSiblings(root->left, data_one,
data_two))
return true ;
// Check for right subtree
if (root->right)
if (CheckIfNodesAreSiblings(root->right, data_one,
data_two))
return true ;
return false ;
} // Driver code int main()
{ struct Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->right->left = newNode(5);
root->right->right = newNode(6);
root->left->left->right = newNode(7);
int data_one = 5;
int data_two = 6;
if (CheckIfNodesAreSiblings(root, data_one, data_two))
cout << "YES" ;
else
cout << "NO" ;
return 0;
} |
// Java program to check if two nodes // are siblings import java.util.*;
class GFG {
// Binary Tree Node
static class Node {
int data;
Node left, right;
};
// Utility function to create a
// new node
static Node newNode( int data)
{
Node node = new Node();
node.data = data;
node.left = node.right = null ;
return (node);
}
static Node root = null ;
// Function to find out if two nodes are siblings
static boolean CheckIfNodesAreSiblings(Node root,
int data_one,
int data_two)
{
if (root == null )
return false ;
// Compare the two given nodes with
// the childrens of current node
if (root.left != null && root.right != null ) {
int left = root.left.data;
int right = root.right.data;
if (left == data_one && right == data_two)
return true ;
else if (left == data_two && right == data_one)
return true ;
}
// Check for left subtree
if (root.left != null )
if (CheckIfNodesAreSiblings(root.left, data_one,
data_two))
return true ;
// Check for right subtree
if (root.right != null )
if (CheckIfNodesAreSiblings(root.right,
data_one, data_two))
return true ;
return false ;
}
// Driver code
public static void main(String[] args)
{
root = newNode( 1 );
root.left = newNode( 2 );
root.right = newNode( 3 );
root.left.left = newNode( 4 );
root.right.left = newNode( 5 );
root.right.right = newNode( 6 );
root.left.left.right = newNode( 7 );
int data_one = 5 ;
int data_two = 6 ;
if (CheckIfNodesAreSiblings(root, data_one,
data_two))
System.out.print( "YES" );
else
System.out.print( "NO" );
}
} // This code is contributed by Rajput-Ji |
# Python3 program to check if two # nodes are siblings # Binary Tree Node class Node:
def __init__( self , key):
self .data = key
self .left = None
self .right = None
# Function to find out if two nodes are siblings def CheckIfNodesAreSiblings(root, data_one,
data_two):
if (root = = None ):
return False
# Compare the two given nodes with
# the childrens of current node
ans = False
if (root.left ! = None and root.right ! = None ):
left = root.left.data
right = root.right.data
if (left = = data_one and right = = data_two):
return True
elif (left = = data_two and right = = data_one):
return True
# Check for left subtree
if (root.left ! = None ):
ans = ans or CheckIfNodesAreSiblings(root.left,
data_one,
data_two)
# Check for right subtree
if (root.right ! = None ):
ans = ans or CheckIfNodesAreSiblings(root.right,
data_one,
data_two)
return ans
# Driver code if __name__ = = '__main__' :
root = Node( 1 )
root.left = Node( 2 )
root.right = Node( 3 )
root.left.left = Node( 4 )
root.right.left = Node( 5 )
root.right.right = Node( 6 )
root.left.left.right = Node( 7 )
data_one = 5
data_two = 6
if (CheckIfNodesAreSiblings(root,
data_one,
data_two)):
print ( "YES" )
else :
print ( "NO" )
# This code is contributed by mohit kumar 29 |
// C# program to check if two nodes // are siblings using System;
// Binary Tree Node public class Node
{ public int data;
public Node left, right;
// Utility function to create a
// new node
public Node( int item)
{
data = item;
left = right = null ;
}
} class GFG{
static Node root = null ;
// Function to find out if two // nodes are siblings static bool CheckIfNodesAreSiblings(Node root,
int data_one,
int data_two)
{ if (root == null )
{
return false ;
}
// Compare the two given nodes with
// the childrens of current node
if (root.left != null && root.right != null )
{
int left = root.left.data;
int right = root.right.data;
if (left == data_one && right == data_two)
{
return true ;
}
else if (left == data_two && right == data_one)
{
return true ;
}
}
// Check for left subtree
if (root.left != null )
{
CheckIfNodesAreSiblings(root.left, data_one,
data_two);
}
// Check for right subtree
if (root.right != null )
{
CheckIfNodesAreSiblings(root.right, data_one,
data_two);
}
return true ;
} // Driver code static public void Main()
{ GFG.root = new Node(1);
GFG.root.left = new Node(2);
GFG.root.right = new Node(3);
GFG.root.left.left = new Node(4);
GFG.root.right.left = new Node(5);
GFG.root.right.right = new Node(6);
GFG.root.left.left.right = new Node(7);
int data_one = 5;
int data_two = 6;
if (CheckIfNodesAreSiblings(root, data_one,
data_two))
{
Console.WriteLine( "YES" );
}
else
{
Console.WriteLine( "NO" );
}
} } // This code is contributed by avanitrachhadiya2155 |
<script> // Javascript program to check if two nodes // are siblings // Binary Tree Node class Node { constructor(data)
{
this .data = data;
this .left = this .right = null ;
}
} let root = null ;
// Function to find out if two nodes are siblings function CheckIfNodesAreSiblings(
root, data_one, data_two)
{ if (root == null )
return false ;
// Compare the two given nodes with
// the childrens of current node
if (root.left != null && root.right != null )
{
let left = root.left.data;
let right = root.right.data;
if (left == data_one &&
right == data_two)
return true ;
else if (left == data_two &&
right == data_one)
return true ;
}
// Check for left subtree
if (root.left != null )
CheckIfNodesAreSiblings(root.left,
data_one,
data_two);
// Check for right subtree
if (root.right != null )
CheckIfNodesAreSiblings(root.right,
data_one,
data_two);
return true ;
} // Driver code root = new Node(1);
root.left = new Node(2);
root.right = new Node(3);
root.left.left = new Node(4);
root.right.left = new Node(5);
root.right.right = new Node(6);
root.left.left.right = new Node(7);
let data_one = 5; let data_two = 6; if (CheckIfNodesAreSiblings(root,
data_one,
data_two))
document.write( "YES" );
else document.write( "NO" );
// This code is contributed by unknown2108 </script> |
YES