Recursive Program to Print extreme nodes of each level of Binary Tree in alternate order
Given a binary tree, the task is to print nodes of extreme corners of each level but in alternate order.
Input : 1 / \ 2 3 / / \ 4 5 6 / / \ 7 8 9 Output : 1 2 6 7 Print the rightmost node at 1st level: 1 Print the leftmost node at 2nd level: 2 Print the rightmost node at 3rd level: 6 Print the leftmost node at 4th level: 7 Other possible output will be -> 1 3 4 9 Input : 3 / \ 8 1 / \ / \ 9 5 6 4 Output : 3 8 4
We have already discussed the iterative approach to solve this problem. In this post the recursive approach is discussed.
Approach: The idea is to perform level order traversal in the spiral form and at each level print the first node during the traversal, these will be the nodes at extreme corner present in the alternate form.
Below is the implementation of the above approach:
1 2 7 8 31
Time Complexity: O(N^2), where N is the total number of nodes in the binary tree.
Auxiliary Space: O(N)