题解 | #序列化二叉树#

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 {
    int INF = 1000;
    TreeNode emptyNode = new TreeNode(INF);
    String Serialize(TreeNode root) {
        if (root == null)return "";
        Queue<TreeNode> q = new LinkedList<>();
        q.add(root);
        StringBuilder sb = new StringBuilder();
        while (!q.isEmpty()) {
            TreeNode cur = q.poll();
            sb.append(cur.val + "#");
            if (!cur.equals(emptyNode)) {
                q.add(cur.left == null ? emptyNode : cur.left);
                q.add(cur.right == null ? emptyNode : cur.right);
            }
        }
        return sb.toString();
    }
    TreeNode Deserialize(String str) {
        if (str == "")return null;
        String[] s = str.split("#");
        TreeNode root = new TreeNode(Integer.parseInt(s[0]));
        Queue<TreeNode> q = new LinkedList<>();
        q.add(root);
        for (int i = 1; i < s.length; i += 2) {
            TreeNode cur = q.poll();
            int left = Integer.parseInt(s[i]), right = Integer.parseInt(s[i + 1]);
            if (left != INF) {
                cur.left = new TreeNode(left);
                q.add(cur.left);
            }
            if (right != INF) {
                cur.right = new TreeNode(right);
                q.add(cur.right);
            }
        }
        return root;
    }
}

利用层序遍历，使用队列解决