题目
In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1.
Two nodes of a binary tree are cousins if they have the same depth, but have different parents.
We are given the root of a binary tree with unique values, and the values x and y of two different nodes in the tree.
Return true if and only if the nodes corresponding to the values x and y are cousins.
解题思路
使用BFS遍历树的每一层，将下一层所有结点放到一个set中，判断x和y是否同时出现在一层中，如果是返回True，只有一个出现返回False，都没有则继续下一层
代码
class Solution:
def isCousins(self, root: TreeNode, x: int, y: int) -> bool:
if root.val == x or root.val == y:
return False
q = {root}
while q:
tmp = set()
for node in q:
if node.left and node.right:
if set([node.left.val, node.right.val]) == set([x, y]):
return False
tmp.add(node.left)
tmp.add(node.right)
else:
tmp.add(node.left or node.right)
q = {n for n in tmp if n is not None}
values = {n.val for n in q}
if x in values and y in values:
return True
if x in values or y in values:
return False
return False
