2415. Reverse Odd Levels of Binary Tree

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def reverseOddLevels(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        q = deque([root])
        i = 0
        while q:
            if i & 1:
                l, r = 0, len(q) - 1
                while l < r:
                    q[l].val, q[r].val = q[r].val, q[l].val
                    l, r = l + 1, r - 1
            for _ in range(len(q)):
                node = q.popleft()
                if node.left:
                    q.append(node.left)
                    q.append(node.right)
            i += 1
        return root