Added Even Odd Tree.java

Author: varunu28

Medium/Even Odd Tree.java

@@ -0,0 +1,49 @@
+/**
+ * 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) {
+    Queue<TreeNode> queue = new LinkedList<>();
+    queue.add(root);
+    int remainderExpected = 1;
+    while (!queue.isEmpty()) {
+      int size = queue.size();
+      Integer prev = null;
+      while (size-- > 0) {
+        TreeNode removed = queue.remove();
+        if (removed.val % 2 != remainderExpected) {
+          return false;
+        }
+        if (prev != null) {
+          if (remainderExpected == 1 && removed.val <= prev) {
+            return false;
+          } 
+          if (remainderExpected == 0 && removed.val >= prev) {
+            return false;
+          } 
+        }
+        prev = removed.val;
+        if (removed.left != null) {
+          queue.add(removed.left);
+        }
+        if (removed.right != null) {
+          queue.add(removed.right);
+        }
+      }
+      remainderExpected = remainderExpected == 1 ? 0 : 1;
+    }
+    return true;
+  }
+}