/**请实现两个函数，分别用来序列化和反序列化二叉树二叉树的序列化是指：把一棵二叉树按照某种遍历方式的结果以某种格式保存为字符串，从而使得内存中建立起来的二叉树可以持久保存。　　　　序列化可以基于先序、中序、后序、层序的二叉树遍历方式来进行修改，序列化的结果是一个字符串，　　　　序列化时通过 某种符号表示空节点（#），以 ！ 表示一个结点值的结束（value!）。二叉树的反序列化是指：根据某种遍历顺序得到的序列化字符串结果str，重构二叉树。
*/

/**先序遍历*/
public class Solution {public int index = -1;/**序列化*/String Serialize(TreeNode root) {StringBuffer sb = new StringBuffer();if(root == null){sb.append("#,");return sb.toString();}sb.append(root.val + ",");//根sb.append(Serialize(root.left));//左sb.append(Serialize(root.right));//右return sb.toString();}/**反序列化*/TreeNode Deserialize(String str) {index++;String[] strr = str.split(",");TreeNode node = null;if(!strr[index].equals("#")){node = new TreeNode(Integer.valueOf(strr[index]));//根node.left = Deserialize(str);//左node.right = Deserialize(str);//右
        }return node;}
}

//采用层序遍历，不需要将转化为完全二叉树的简单方法
public class Solution {String Serialize(TreeNode root) {StringBuilder sb = new StringBuilder();Queue<TreeNode> queue = new LinkedList<TreeNode>();if(root != null)queue.add(root);while(!queue.isEmpty()){TreeNode node = queue.poll();if(node != null){queue.offer(node.left);queue.offer(node.right);sb.append(node.val + ",");}else{sb.append("#" + ",");}}if(sb.length() != 0)sb.deleteCharAt(sb.length()-1);return sb.toString();}TreeNode Deserialize(String str) {TreeNode head = null;if(str == null || str.length() == 0)return head;String[] nodes = str.split(",");TreeNode[] treeNodes = new TreeNode[nodes.length];for(int i=0; i<nodes.length; i++){if(!nodes[i].equals("#"))treeNodes[i] = new TreeNode(Integer.valueOf(nodes[i]));}for(int i=0, j=1; j<treeNodes.length; i++){if(treeNodes[i] != null){treeNodes[i].left = treeNodes[j++];treeNodes[i].right = treeNodes[j++];}}return treeNodes[0];}
}