leetcode-449-Serialize-and-Deserialize-BST

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描述

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.

Design an algorithm to serialize and deserialize a binary search tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary search tree can be serialized to a string and this string can be deserialized to the original tree structure.

The encoded string should be as compact as possible.

Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.

分析

跟 297. Serialize and Deserialize Binary Tree 简直一模一样。

解决方案1(Java)

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/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Codec {

    // Encodes a tree to a single string.
    public String serialize(TreeNode root) {
        StringBuilder sb = new StringBuilder();
        tree2String(root, sb);
        return sb.toString();
    }
    
    private void tree2String(TreeNode node, StringBuilder sb) {
        if (node == null) {
            sb.append("#").append(" ");
            return;
        }
        sb.append(node.val).append(" ");
        tree2String(node.left, sb);
        tree2String(node.right, sb);
        
    }

    // Decodes your encoded data to tree.
    public TreeNode deserialize(String data) {
        Deque<String> nodes = new LinkedList<>();
        nodes.addAll(Arrays.asList(data.split(" ")));
        return string2Tree(nodes);
    }
    
    private TreeNode string2Tree(Deque<String> nodes) {
        String val = nodes.remove();
        if (val.equals("#")) {
            return null;
        }
        TreeNode node = new TreeNode(Integer.valueOf(val));
        node.left = string2Tree(nodes);
        node.right = string2Tree(nodes);
        return node;
    }
}

// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.deserialize(codec.serialize(root));

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