606. 根据二叉树创建字符串

「爱情、让人受尽委屈。」 2022-12-19 00:51 135阅读 0赞

# 题目来源 #

[606. 根据二叉树创建字符串][606.]

# 题目描述 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70_pic_center]

# 题目解析 #

## 递归 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70_pic_center 1]

/**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     int val;
     *     TreeNode left;
     *     TreeNode right;
     *     TreeNode(int x) { val = x; }
     * }
     */
    class Solution {
        
    private StringBuilder stringBuilder = new StringBuilder();
        public String tree2str(TreeNode t) {
        
    
            helper(t);
            return stringBuilder.toString();
        }
    
        private void helper(TreeNode root){
        
            if (root == null){
        
                return;
            }
    
            stringBuilder.append(root.val);
    
            if (root.left == null && root.right == null){
        
                return;
            }
    
            if (root.left != null){
        
                stringBuilder.append("(");
                helper(root.left);
                stringBuilder.append(")");
            }else{
        
                stringBuilder.append("()");
            }
    
            if (root.right != null){
        
                stringBuilder.append("(");
                helper(root.right);
                stringBuilder.append(")");
            }
        }
    }

![在这里插入图片描述][20201104202116453.png_pic_center]

[606.]: https://leetcode-cn.com/problems/construct-string-from-binary-tree/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/7fa56741f77b4491b65acee2a65e6366.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70_pic_center 1]: https://img-blog.csdnimg.cn/20201104202103579.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg==,size_16,color_FFFFFF,t_70#pic_center
[20201104202116453.png_pic_center]: https://img-blog.csdnimg.cn/20201104202116453.png#pic_center