剑指Offer_61

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题目

请实现两个函数，分别用来序列化和反序列化二叉树

解题思路

序列化二叉树：

前序遍历二叉树

反序列化二叉树：

根据“＃” 的值判断是否应该构造节点

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/*
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) {
        StringBuffer sb = new StringBuffer();
        if(root == null){
            sb.append("#,");
            return sb.toString();
        }
        sb.append(root.val + ",");
        sb.append(Serialize(root.left));
  		sb.append(Serialize(root.right));
        
        return sb.toString();
    }
    
    private int index;
    private TreeNode DeserializeHelper(String []strings){
        ++index;
        TreeNode node = null;
        if(!strings[index].equals("#")){
            node = new TreeNode(Integer.valueOf(strings[index]));
            node.left = DeserializeHelper(strings);
            node.right = DeserializeHelper(strings);
        }
        return node;
    }
    
    TreeNode Deserialize(String str) {
        index = -1;
        String []strings = str.split(",");
        return DeserializeHelper(strings);
  	}
    
}