Add solution #1609

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,417 LeetCode solutions in JavaScript
+# 1,418 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1241,6 +1241,7 @@
 1604|[Alert Using Same Key-Card Three or More Times in a One Hour Period](./solutions/1604-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period.js)|Medium|
 1605|[Find Valid Matrix Given Row and Column Sums](./solutions/1605-find-valid-matrix-given-row-and-column-sums.js)|Medium|
 1608|[Special Array With X Elements Greater Than or Equal X](./solutions/1608-special-array-with-x-elements-greater-than-or-equal-x.js)|Easy|
+1609|[Even Odd Tree](./solutions/1609-even-odd-tree.js)|Medium|
 1657|[Determine if Two Strings Are Close](./solutions/1657-determine-if-two-strings-are-close.js)|Medium|
 1668|[Maximum Repeating Substring](./solutions/1668-maximum-repeating-substring.js)|Easy|
 1669|[Merge In Between Linked Lists](./solutions/1669-merge-in-between-linked-lists.js)|Medium|

solutions/1609-even-odd-tree.js

@@ -0,0 +1,57 @@
+/**
+ * 1609. Even Odd Tree
+ * https://leetcode.com/problems/even-odd-tree/
+ * Difficulty: Medium
+ *
+ * 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.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {boolean}
+ */
+var isEvenOddTree = function(root) {
+  let queue = [root];
+  let level = 0;
+
+  while (queue.length) {
+    const levelSize = queue.length;
+    let prevValue = level % 2 === 0 ? -Infinity : Infinity;
+    const newQueue = [];
+
+    for (let i = 0; i < levelSize; i++) {
+      const node = queue[i];
+      const isEvenLevel = level % 2 === 0;
+      const isOddValue = node.val % 2 === 1;
+
+      if (isEvenLevel && (!isOddValue || node.val <= prevValue)) return false;
+      if (!isEvenLevel && (isOddValue || node.val >= prevValue)) return false;
+
+      prevValue = node.val;
+      if (node.left) newQueue.push(node.left);
+      if (node.right) newQueue.push(node.right);
+    }
+
+    queue = newQueue;
+    level++;
+  }
+
+  return true;
+};