剑指offer-序列化二叉树

/*
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) {
        if(root == null){
            return "#!";
        }
        //前序遍历生成字符串
        return root.val+"!"+Serialize(root.left)+Serialize(root.right);
    }
    TreeNode Deserialize(String str) {
       return str2tree(str.split("!"));
    }
    private int pos = 0;
    TreeNode str2tree(String[] arr){
        if(pos >= arr.length){
            return null;
        }
        if(arr[pos].equals("#")){
            return null;
        }
        TreeNode node = new TreeNode(Integer.valueOf(arr[pos]));
        //左节点位置++
        pos++;
        node.left = str2tree(arr);
        //右节点位置++
        pos++;
        node.right = str2tree(arr);
        return node;
    }
}