Merge pull request #3562 from aadil42/patch-98

Create 1609-even-odd-tree.js

Author: Ykhan799

javascript/1609-even-odd-tree.js

@@ -0,0 +1,67 @@
+/**
+ * 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)
+ * }
+ */
+
+/**
+ * Level Order Traversal | BFS
+ * Time O(n) | Space O(n)
+ * https://leetcode.com/problems/even-odd-tree
+ * @param {TreeNode} root
+ * @return {boolean}
+ */
+var isEvenOddTree = function(root) {
+
+    // helper function
+    const isStricklyIncreasingAndOdd = (arr) => {
+
+        for (let i = 0; i < arr.length; i++) {
+            const currElement = arr[i];
+            const nextElement = (arr[i+1] !== undefined && arr[i+1]) || Infinity;
+            if (currElement >= nextElement || currElement%2 === 0) return false;
+        }
+
+        return true;
+    }
+    
+    // helper function
+    const isStricklyDecreasingAndEven = (arr) => {
+
+        for (let i = 0; i < arr.length; i++) {
+            const currElement = arr[i];
+            const nextElement = (arr[i+1] !== undefined && arr[i+1]) || -Infinity;
+            if (currElement <= nextElement || currElement%2 === 1) return false;
+        }
+
+        return true;
+    }
+
+    const q = new Queue();
+    q.enqueue([root, 0]);
+
+    while (!q.isEmpty()) {
+        const size = q.size();
+
+        const levelArr = [];
+        const level = q.front()[1];
+
+        for (let i = 0; i < size; i++) {
+
+            const element = q.dequeue();
+            const node = element[0];
+            levelArr.push(node.val);
+
+            node.left && q.enqueue([node.left, level+1]);
+            node.right && q.enqueue([node.right, level+1]);
+        }
+
+        if (level%2 === 0 && !isStricklyIncreasingAndOdd(levelArr)) return false;
+        if (level%2 === 1 && !isStricklyDecreasingAndEven(levelArr)) return false;
+    }
+
+    return true;
+};