Update 二叉树相关.md

blogs/Algorithm/剑指 Offer/二叉树相关.md

@@ -4,7 +4,16 @@
 
 #### 目录
 
-1. #### [07. 重建二叉树](https://leetcode-cn.com/problems/zhong-jian-er-cha-shu-lcof/)
+1. [07. 重建二叉树](https://leetcode-cn.com/problems/zhong-jian-er-cha-shu-lcof/)
+2. [26. 树的子结构](https://leetcode-cn.com/problems/shu-de-zi-jie-gou-lcof/)
+3. [ 27. 二叉树的镜像](https://leetcode-cn.com/problems/er-cha-shu-de-jing-xiang-lcof/)
+4. [32 - I. 从上到下打印二叉树](https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-lcof/)
+5. [ Offer 34. 二叉树中和为某一值的路径](https://leetcode-cn.com/problems/er-cha-shu-zhong-he-wei-mou-yi-zhi-de-lu-jing-lcof/)
+6. [55 - I. 二叉树的深度](https://leetcode-cn.com/problems/er-cha-shu-de-shen-du-lcof/)
+7. [55 - II. 平衡二叉树](https://leetcode-cn.com/problems/ping-heng-er-cha-shu-lcof/)
+8. [32 - II. 从上到下打印二叉树 II](https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-ii-lcof/)
+9. [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/)
+10. [37. 序列化二叉树](https://leetcode-cn.com/problems/xu-lie-hua-er-cha-shu-lcof/)
 
 #### [07. 重建二叉树](https://leetcode-cn.com/problems/zhong-jian-er-cha-shu-lcof/)
 
@@ -360,3 +369,59 @@ class Solution {
 }
 ```
 
+#### [37. 序列化二叉树](https://leetcode-cn.com/problems/xu-lie-hua-er-cha-shu-lcof/)
+
+```java
+public class Codec {
+
+    // Encodes a tree to a single string.
+    public String serialize(TreeNode root) {
+        if (root == null) {
+            return "[]";
+        }
+        Deque<TreeNode> deque = new LinkedList<>();
+        deque.add(root);
+        StringBuilder builder = new StringBuilder("[");
+        while (!deque.isEmpty()) {
+            TreeNode node = deque.poll();
+            if (node != null) {
+                builder.append(node.val).append(",");
+                deque.add(node.left);
+                deque.add(node.right);
+            } else {
+                builder.append("null,");
+            }
+        }
+        builder.deleteCharAt(builder.length() - 1);
+        builder.append("]");
+        return builder.toString();
+    }
+
+    // Decodes your encoded data to tree.
+    public TreeNode deserialize(String data) {
+        if ("[]".equals(data)) {
+            return null;
+        }
+        String[] vals = data.substring(1, data.length() - 1).split(",");
+        TreeNode root = new TreeNode(Integer.parseInt(vals[0]));
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.add(root);
+        int i = 1;
+        while (!queue.isEmpty()) {
+            TreeNode node = queue.poll();
+            if (!vals[i].equals("null")) {
+                node.left = new TreeNode(Integer.parseInt(vals[i]));
+                queue.add(node.left);
+            }
+            i++;
+            if (!vals[i].equals("null")) {
+                node.right = new TreeNode(Integer.parseInt(vals[i]));
+                queue.add(node.right);
+            }
+            i++;
+        }
+        return root;
+    }
+}
+```
+