题解 |#序列化二叉树（层序）#

层序大法好啊

import java.util.*;

/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    String Serialize(TreeNode root) {
        if (root == null) {
            return "";
        }

        LinkedList<TreeNode> queue = new LinkedList<>();
        StringBuffer res = new StringBuffer();
        res.append(root.val + " ");
        queue.offer(root);

        while (!queue.isEmpty()) {

            int size = queue.size();

            while (size > 0) {
                TreeNode node = queue.poll();

                if (node.left != null) {
                    res.append(node.left.val + " ");
                    queue.offer(node.left);
                } else {
                    res.append("# ");
                }

                if (node.right != null) {
                    res.append(node.right.val + " ");
                    queue.offer(node.right);
                } else {
                    res.append("# ");
                }

                size--;
            }
        }

        return res.toString();
  }
    TreeNode Deserialize(String str) {
       if (str.equals("")) {
           return null;
       }

        String[] s = str.split(" ");

        LinkedList<TreeNode> queue = new LinkedList<>();

        TreeNode root = new TreeNode(Integer.valueOf(s[0]));

        queue.offer(root);
        int index = 1;
        while (!queue.isEmpty()) {

            int size = queue.size();

            while (size > 0) {
                TreeNode node = queue.poll();

                if (!s[index].equals("#")) {
                    node.left = new TreeNode(Integer.valueOf(s[index]));
                    queue.offer(node.left);
                }
                index++;

                if (!s[index].equals("#")) {
                    node.right = new TreeNode(Integer.valueOf(s[index]));
                    queue.offer(node.right);
                }
                index++;

                size--;
            }
        }

        return root;
  }
}