993. Cousins in Binary Tree

Author: Partho Biswas

README.md

@@ -411,6 +411,7 @@ Check this [golden](https://tinyurl.com/ujopecz) post.
 |30| **[236. Lowest Common Ancestor of a Binary Tree](https://tinyurl.com/y54e6gco)**| [Python](https://tinyurl.com/wu6rdaw/236_Lowest_Common_Ancestor_of_a_Binary_Tree.py)| **[Vid 1](https://tinyurl.com/udf9oa9)**, **[Vid 2](https://tinyurl.com/stknbyu)**, **[Algoexpert.io](https://tinyurl.com/wwz4m5t)**, **[Official](https://tinyurl.com/yx28t8ff)**, **[Art 1](https://tinyurl.com/v86wcky)**, **[Art 2](https://tinyurl.com/tu7jdzq)**, **[Art 3](https://tinyurl.com/tgvyy7p)** | Medium | TODO: Check Again. Very Important |
 |31| **[114. Flatten Binary Tree to Linked List](https://tinyurl.com/yyc6ol5w)**| [Python](https://tinyurl.com/wu6rdaw/114_Flatten_Binary_Tree_to_Linked_List.py)| [Art 1](https://tinyurl.com/v5s5axv) | Medium | Classic Prolem |
 |32| **[297. Serialize and Deserialize Binary Tree](https://tinyurl.com/ycfugzww)**| [Python](https://tinyurl.com/wu6rdaw/297_Serialize_and_Deserialize_Binary_Tree.py), [Swift](https://tinyurl.com/wuja3c4/297_Serialize_and_Deserialize_Binary_Tree.swift) | [Vid 1](https://tinyurl.com/yx4w25u4) | Hard | Classic Prolem |
+|33| **[993. Cousins in Binary Tree](https://tinyurl.com/ybtzjhnb)**| [Python](https://tinyurl.com/wu6rdaw/993_Cousins_in_Binary_Tree.py), [Swift](https://tinyurl.com/wuja3c4/993_Cousins_in_Binary_Tree.swift) |  | Easy(Not so) |  |
 
 </p>
 </details>

leetcode.com/python/993_Cousins_in_Binary_Tree.py

@@ -0,0 +1,36 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution(object):
+    def isCousins(self, root, x, y):
+        """
+        :type root: TreeNode
+        :type x: int
+        :type y: int
+        :rtype: bool
+        """
+        xLevel, xParent = self.isCousinsHelperDFS(root, None, 0, x)
+        yLevel, yParent = self.isCousinsHelperDFS(root, None, 0, y)
+
+        if xParent and yParent and (xParent != yParent) and (xLevel == yLevel):
+            return True
+        else:
+            return False
+
+    def isCousinsHelperDFS(self, node, parent, currentLevel, x):
+        if not node:
+            return (0, None)
+        if node.val == x:
+            return (currentLevel, parent)
+
+        leftLevel, leftParent = self.isCousinsHelperDFS(node.left, node, currentLevel + 1, x)
+        rightLevel, rightParent = self.isCousinsHelperDFS(node.right, node, currentLevel + 1, x)
+        if leftParent:
+            return (leftLevel, leftParent)
+        else:
+            return (rightLevel, rightParent)
+
+