2025-08-01 17:14:01 +0000 UTC

# 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 isCousins(self, root: Optional[TreeNode], x: int, y: int) -> bool:
        def dfs(node: Optional[TreeNode], depth: int) -> tuple[int, int]:
            if node is None:
                return 0, 0
            if node.val == x:
                return depth, 0
            if node.val == y:
                return 0, depth
            depth1_x, depth1_y = dfs(node.left, depth + 1)
            depth2_x, depth2_y = dfs(node.right, depth + 1)
            depth1, depth2 = depth1_x or depth2_x, depth1_y or depth2_y
            if depth1 and depth2 and depth1 == depth + 1:
                return 0, 0
            return depth1, depth2

        depth1, depth2 = dfs(root, 0)
        return depth1 == depth2 and depth1 > 1