951 Flip Equivalent Binary Trees.py

Author: rajeevranjancom

951 Flip Equivalent Binary Trees.py

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+#!/usr/bin/python3
+"""
+For a binary tree T, we can define a flip operation as follows: choose any node,
+and swap the left and right child subtrees.
+
+A binary tree X is flip equivalent to a binary tree Y if and only if we can make
+X equal to Y after some number of flip operations.
+
+Write a function that determines whether two binary trees are flip equivalent.
+The trees are given by root nodes root1 and root2.
+
+
+
+Example 1:
+
+Input: root1 = [1,2,3,4,5,6,null,null,null,7,8], root2 = [1,3,2,null,6,4,5,null,null,null,null,8,7]
+Output: true
+Explanation: We flipped at nodes with values 1, 3, and 5.
+Flipped Trees Diagram
+
+
+Note:
+
+Each tree will have at most 100 nodes.
+Each value in each tree will be a unique integer in the range [0, 99].
+"""
+
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+
+class Solution:
+    def flipEquiv(self, root1: TreeNode, root2: TreeNode) -> bool:
+        """
+        O(N)
+        """
+        if not root1 and not root2:
+            return True
+        elif not root1 or not root2:
+            return False
+
+        if root1.val != root2.val:
+            return False
+
+        return self.flipEquiv(root1.left, root2.left) and self.flipEquiv(root1.right, root2.right) or \
+            self.flipEquiv(root1.left, root2.right) and self.flipEquiv(root1.right, root2.left)