Given a binary tree, the task is to print the nodes of the tree in a reverse anti-clockwise spiral manner.
Input : 1 / \ 2 3 / \ \ 4 5 6 / / \ 7 8 9 Output : 7 8 9 1 4 5 6 3 2 Input : 20 / \ 8 22 / \ / \ 5 3 4 25 / \ 10 14 Output : 10 14 20 5 3 4 25 22 8
Approach: The idea is to use two variables i initialized to 1 and j initialized to the height of tree and run a while loop which wont break until i becomes greater than j. We will use another variable flag and initialize it to 1. Now in the while loop we will check a condition that if flag is equal to 1 we will traverse the tree from left to right and mark flag as 0 so that next time we traverse the tree from right to left and then decrement the value of j so that next time we visit the level just above the current level. Also when we will traverse the level from top we will mark flag as 1 so that next time we traverse the tree from left to right and then increment the value of i so that next time we visit the level just below the current level. Repeat the whole process until the binary tree is completely traversed.
Below is the implementation of the above approach:
10 14 20 5 3 4 25 22 8
Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.
- Anti Clockwise spiral traversal of a binary tree
- Reverse Clockwise spiral traversal of a binary tree
- Clockwise Spiral Traversal of Binary Tree
- Clockwise Spiral Traversal of Binary Tree | Set - 2
- Clockwise Triangular traversal of a Binary Tree
- Element in a matrix starting from which anti-clockwise traversal ends at the last element
- Reverse zigzag Traversal of a Binary Tree
- Reverse Morris traversal using Threaded Binary Tree
- Reverse Level Order traversal in spiral form
- Level order traversal of Binary Tree using Morris Traversal
- Check if a binary tree is subtree of another binary tree using preorder traversal : Iterative
- Construct Full Binary Tree using its Preorder traversal and Preorder traversal of its mirror tree
- Maximum spiral sum in Binary Tree
- Given level order traversal of a Binary Tree, check if the Tree is a Min-Heap
- Convert a Binary Tree into Doubly Linked List in spiral fashion
- Zig-Zag traversal of a Binary Tree using Recursion
- Density of Binary Tree in One Traversal
- Boundary Traversal of binary tree
- Diagonal Traversal of Binary Tree
- Kth node in Diagonal Traversal of Binary Tree
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to email@example.com. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.