23 lines
832 B
Python
23 lines
832 B
Python
# https://leetcode.com/problems/reverse-odd-levels-of-binary-tree
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from typing import Optional
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class TreeNode:
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def __init__(self, val=0, left=None, right=None):
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self.val = val
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self.left = left
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self.right = right
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class Solution:
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def reverseOddLevels(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
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def traverse(left: Optional[TreeNode], right: Optional[TreeNode], depth: int):
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if left is None or right is None:
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return
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if depth % 2 == 1:
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tmp = left.val
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left.val = right.val
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right.val = tmp
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traverse(left.left, right.right, depth + 1)
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traverse(left.right, right.left, depth + 1)
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if root is not None:
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traverse(root.left, root.right, 1)
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return root
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