二叉树的序列化及反序列化
力扣：297题。序列化：将一个数据结构或对象转换为连续的比特位的操作，进而可以将转换后的数据存储在一个文件或内存中，同事也可以通过网络传输到另一个计算环境中，采取相反方式重构得到原数据。
请设计一个算法来实现二叉树的序列化与反序列化，这里不限定你的序列化与反序列化逻辑，只要保证一个二叉树可以被序列化为一个字符串，并可以将这个字符串反序列化为原始的树即可。
思路：通过二叉树的前序遍历来实现。误区，没有好好理解题意，不用非要加”[]“,来与案例一样。
public class Codec {//Encodes a tree to a single string//利用队列的方式实现public String serialize(TreeNode root){Queue<TreeNode> queue = new LinkedList<>();if (root !=null){queue.add(root);}StringBuffer buffer = new StringBuffer();buffer.append("[");while (!queue.isEmpty()){TreeNode poll = queue.poll();String value =String.valueOf(poll.val);buffer.append(value).append(",");if (poll.left !=null){queue.add(poll.left);}else {value= "null";buffer.append(value).append(",");}if (poll.right !=null){queue.add(poll.right);}else {value= "null";buffer.append(value).append(",");}}String s = buffer.toString();buffer.replace(s.length()-1,s.length(),"]");String result = buffer.toString();return result;}public String serialize1(TreeNode root) {return rserialize(root, "");}public String rserialize(TreeNode root, String str) {if (root == null) {str += "None,";} else {str += str.valueOf(root.val) + ",";str = rserialize(root.left, str);str = rserialize(root.right, str);}return str;}//Decodes your encoded data to treepublic TreeNode deserialize(String data){String[] split = data.split(",");ArrayList<String> data_list = new ArrayList<>(Arrays.asList(split));return reserialize(data_list);}private TreeNode reserialize(ArrayList<String> data_list) {if (data_list.get(0).equals("None")){data_list.remove(0);return null;}TreeNode node = new TreeNode(Integer.valueOf(data_list.get(0)));data_list.remove(0);node.left = reserialize(data_list);node.right = reserialize(data_list);return node;}}class TreeNode{int val;TreeNode left;TreeNode right;TreeNode(int x) { val = x; }}