Update 二叉树相关.md

blogs/Algorithm/剑指 Offer/二叉树相关.md

@@ -325,3 +325,38 @@ class Solution {
 }
 ```
 
+#### [32 - III. 从上到下打印二叉树 III](https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-iii-lcof/)
+
+```java
+class Solution {
+
+    public List<List<Integer>> levelOrder(TreeNode root) {
+        List<List<Integer>> res = new ArrayList<>();
+        if (root == null) {
+            return res;
+        }
+        Deque<TreeNode> deque = new LinkedList<>();
+        deque.add(root);
+        while (!deque.isEmpty()) {
+            int l = deque.size();
+            List<Integer> list = new ArrayList<>(l);
+            for (int i = 0; i < l; i++) {
+                TreeNode node = deque.poll();
+                list.add(node.val);
+                if (node.left != null) {
+                    deque.add(node.left);
+                }
+                if (node.right != null) {
+                    deque.add(node.right);
+                }
+            }
+            if (res.size() % 2 == 1) {
+                Collections.reverse(list);
+            }
+            res.add(list);
+        }
+        return res;
+    }
+}
+```
+