Even Odd Tree

A binary tree is named Even-Odd if it meets the following conditions:

The root of the binary tree is at level index 0, its children are at level index 1, their children are at level index 2, etc.
For every even-indexed level, all nodes at the level have odd integer values in strictly increasing order (from left to right).
For every odd-indexed level, all nodes at the level have even integer values in strictly decreasing order (from left to right).

Given the root of a binary tree, return true if the binary tree is Even-Odd, otherwise return false.

Example 1:

Input: root = [1,10,4,3,null,7,9,12,8,6,null,null,2]
Output: true
Explanation: The node values on each level are:
Level 0: [1]
Level 1: [10,4]
Level 2: [3,7,9]
Level 3: [12,8,6,2]
Since levels 0 and 2 are all odd and increasing, and levels 1 and 3 are all even and decreasing, the tree is Even-Odd.

Example 2:

Input: root = [5,4,2,3,3,7]
Output: false
Explanation: The node values on each level are:
Level 0: [5]
Level 1: [4,2]
Level 2: [3,3,7]
Node values in the level 2 must be in strictly increasing order, so the tree is not Even-Odd.

Example 3:

Input: root = [5,9,1,3,5,7]
Output: false
Explanation: Node values in the level 1 should be even integers.

Example 4:

Input: root = [1]
Output: true

Example 5:

Input: root = [11,8,6,1,3,9,11,30,20,18,16,12,10,4,2,17]
Output: true

Constraints:

The number of nodes in the tree is in the range [1, 105].
1 <= Node.val <= 106

Solution:

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean isEvenOddTree(TreeNode root) {
        if (root.val % 2 == 0) return false;
        Deque<TreeNode> queue = new ArrayDeque();
        int level = 0;
        queue.offer(root);
        while (!queue.isEmpty()) {
            int size = queue.size();
            int prevEven = Integer.MAX_VALUE, prevOdd = Integer.MIN_VALUE;
            for (int i = 0; i < size; i ++) {
                TreeNode curr = queue.poll();
                if (level % 2 == 0) {
                    // even level should have odd value increasing
                    if (curr.val % 2 == 0 || curr.val <= prevOdd) {
                        // System.out.println(level + ": " + curr.val);
                        return false;
                    }
                    prevOdd = curr.val;
                } else {
                    if (curr.val % 2 == 1 || curr.val >= prevEven) {
                        // System.out.println(level + ": " + curr.val);
                        return false;
                    }
                    prevEven = curr.val;
                }
                if (curr.left != null) queue.offer(curr.left);
                if (curr.right != null) queue.offer(curr.right);
            }
            level ++;
        }
        return true;
    }
}