Given a binary tree and the two nodes say ‘a’ and ‘b’, determine whether two given nodes are cousins of each other or not.
Two nodes are cousins of each other if they are at same level and have different parents.
6 / \ 3 5 / \ / \ 7 8 1 3 Say two node be 7 and 1, result is TRUE. Say two nodes are 3 and 5, result is FALSE. Say two nodes are 7 and 5, result is FALSE.
A solution in Set-1 that finds whether given nodes are cousins or not by performing three traversals of binary tree has been discussed. The problem can be solved by performing level order traversal. The idea is to use a queue to perform level order traversal, in which each queue element is a pair of node and parent of that node. For each node visited in level order traversal, check if that node is either first given node or second given node. If any node is found store parent of that node. While performing level order traversal, one level is traversed at a time. If both nodes are found in given level, then their parent values are compared to check if they are siblings or not. If one node is found in given level and another is not found, then given nodes are not cousins.
Below is the implementation of above approach:
Time Complexity: O(n)
Auxiliary Space: O(n)
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