LeetCode in Kotlin
951. Flip Equivalent Binary Trees
Medium
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.
Given the roots of two binary trees root1 and root2, return true if the two trees are flip equivalent or false otherwise.
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.
Example 2:
Input: root1 = [], root2 = []
Output: true
Example 3:
Input: root1 = [], root2 = [1]
Output: false
Constraints:
- The number of nodes in each tree is in the range
[0, 100]. - Each tree will have unique node values in the range
[0, 99].
Solution
import com_github_leetcode.TreeNode
/*
* Example:
* var ti = TreeNode(5)
* var v = ti.`val`
* Definition for a binary tree node.
* class TreeNode(var `val`: Int) {
* var left: TreeNode? = null
* var right: TreeNode? = null
* }
*/
class Solution {
fun flipEquiv(root1: TreeNode?, root2: TreeNode?): Boolean {
if (root1 == null && root2 == null) {
return true
}
if (root1 == null || root2 == null) {
return false
}
return if (root1.`val` != root2.`val`) {
false
} else {
flipEquiv(root1.left, root2.left) && flipEquiv(root1.right, root2.right) ||
flipEquiv(root1.left, root2.right) && flipEquiv(root1.right, root2.left)
}
}
}