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 {
    String Serialize(TreeNode root) {
        StringBuilder sb =  new StringBuilder();
        sb.append("{");
        if (root == null) {
            sb.append("#");
        } else {
            Queue<TreeNode> q =  new LinkedList();
            q.offer(root);
            while (!q.isEmpty()) {
                TreeNode t = q.poll();
                if (t != null) {
                    sb.append(t.val);
                    sb.append(",");
                    q.offer(t.left);
                    q.offer(t.right);
                } else {
                    sb.append("#");
                    sb.append(",");

                }
            }
        }

        char tail = sb.charAt(sb.length() - 1);
        while (tail == ',' || tail == '#') {
            sb.deleteCharAt(sb.length() - 1);
            tail = sb.charAt(sb.length() - 1);
        }

        sb.append("}");
        return sb.toString();
    }
    TreeNode Deserialize(String str) {
        str=str.substring(1,str.length()-1);
         String [] nodes = str.split(",");
        if(nodes.length==0 || nodes[0].equals(""))return null;
        int i = 0;
        Queue<TreeNode> q = new LinkedList<>();
        TreeNode root = new TreeNode(Integer.parseInt(nodes[0]));
        q.offer(root);
        i++;
        while(!q.isEmpty()&&i<nodes.length){
            TreeNode cur = q.poll();
            if(nodes[i].equals("#")){
                cur.left=null;

            }else{
                TreeNode left = new TreeNode(Integer.parseInt(nodes[i]));
                cur.left = left;
                q.offer(left);
            }
            i++;
            if(i>=nodes.length)break;

            if(nodes[i].equals("#")){
                cur.right=null;

            }else{
                TreeNode right = new TreeNode(Integer.parseInt(nodes[i]));
                cur.right = right;
                q.offer(right);
            }
            i++;

        }

        return root;
    }
}