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.
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. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public boolean flipEquiv(TreeNode root1, TreeNode root2) { if (root1 == null && root2 == null) return true; if (root1 == null || root2 == null) return false; if (root1.val != root2.val) return false; return (flipEquiv(root1.left, root2.right) && flipEquiv(root1.right, root2.left)) || (flipEquiv(root1.left, root2.left) && flipEquiv(root1.right, root2.right)); } }
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