Given the root of a perfect binary tree, reverse the node values at each odd level of the tree.
[2,1,3,4,7,11,29,18], then it should become [18,29,11,7,4,3,1,2].Return the root of the reversed tree.
A binary tree is perfect if all parent nodes have two children and all leaves are on the same level.
The level of a node is the number of edges along the path between it and the root node.
Example 1:
Input: root = [2,3,5,8,13,21,34] Output: [2,5,3,8,13,21,34] Explanation: The tree has only one odd level. The nodes at level 1 are 3, 5 respectively, which are reversed and become 5, 3.
Example 2:
Input: root = [7,13,11] Output: [7,11,13] Explanation: The nodes at level 1 are 13, 11, which are reversed and become 11, 13.
Example 3:
Input: root = [0,1,2,0,0,0,0,1,1,1,1,2,2,2,2] Output: [0,2,1,0,0,0,0,2,2,2,2,1,1,1,1] Explanation: The odd levels have non-zero values. The nodes at level 1 were 1, 2, and are 2, 1 after the reversal. The nodes at level 3 were 1, 1, 1, 1, 2, 2, 2, 2, and are 2, 2, 2, 2, 1, 1, 1, 1 after the reversal.
Constraints:
[1, 214].0 <= Node.val <= 105root is a perfect binary tree.This approach involves iterating through each conceivable solution space or list and checking which solutions satisfy the given problem. It's straightforward but may not be optimized for time complexity, making it suitable for problems with limited input sizes or as a stepping stone to more efficient methods.
This C program defines a function to print "Hello, World!" and calls that function within the main function.
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Time Complexity: O(1)
Space Complexity: O(1)
This approach leverages tailored iteration strategies to resolve the problem more efficiently, especially when dealing with larger datasets. It eliminates some of the redundancies present in a brute force solution.
This C code scans the string using a counting array to track the frequency of each character. It promptly returns any character that appears more than once.
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Time Complexity: O(n)
Space Complexity: O(1) because number of characters is constant.
| Approach | Complexity |
|---|---|
| Approach 1: Brute Force Method | Time Complexity: O(1) |
| Approach 2: Optimized Iterative Approach | Time Complexity: O(n) |
Reverse Odd Levels of Binary Tree | Detailed | DFS | BFS | Leetcode 2415 | codestorywithMIK • codestorywithMIK • 6,813 views views
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