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.
Example 1:
Input: root = [1,2,3,4], x = 4, y = 3
Output: false
Example 2:
Input: root = [1,2,3,null,4,null,5], x = 5, y = 4
Output: true
Example 3:
Input: root = [1,2,3,null,4], x = 2, y = 3
Output: false
Note:
The number of nodes in the tree will be between 2 and 100.
Each node has a unique integer value from 1 to 100.
class Solution:
m = {}
def isCousins(self, root, x, y):
if not root:
return False
if self.depth(root, x) == self.depth(root, y):
return self.m[x] != self.m[y]
return False
def depth(self, root, val):
if not root:
return -1
if root.val == val:
return 0
else:
left = self.depth(root.left, val)
right = self.depth(root.right, val)
if left >= 0:
self.m[root.left.val] = root.val
return 1 + left
elif right >= 0:
self.m[root.right.val] = root.val
return 1 + right
return -1