剑指offer-序列化二叉树

序列化二叉树

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;

class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;
    public TreeNode(int val) {
        this.val = val;
    }
}
public class Solution {
    int index = -1;//字符数组指针 
    String Serialize(TreeNode root) {     //将树序列化成字符串
        if(root == null) return "#";
        return "" + root.val + " " + Serialize(root.left) + " " + Serialize(root.right);
//        StringBuilder sb = new StringBuilder();
//        if(root == null) {
//            return sb.append("#,").toString();
//        }
//        sb.append(root.val + ",");
//        sb.append(Serialize(root.left));
//        sb.append(Serialize(root.right));
//        return sb.toString();
  }
    TreeNode Deserialize(String str) {
       index++;
       String[] strr = str.split(" ");
       if(strr[index].equals("#")) return null;
       TreeNode node = new TreeNode(Integer.valueOf(strr[index]));
       node.left = Deserialize(str);
       node.right = Deserialize(str);
       return node;
  }
    
     
    //层次打印二叉树
   public static ArrayList<Integer> PrintFromTopToBottom(TreeNode root) {
        Queue<TreeNode> queue = new LinkedList<>();
        ArrayList<Integer> ret = new ArrayList<>();
        queue.add(root);
        while(!queue.isEmpty()) {
            TreeNode t = queue.poll();
            if(t == null) continue;
            ret.add(t.val);
            queue.add(t.left);
            queue.add(t.right);
        }
        return ret;
    }
    public static void main(String[] args) {
        Solution solution = new Solution();
        TreeNode s = new TreeNode(1);
        s.left = new TreeNode(2);
        s.right = new TreeNode(3);
        s.left.left = new TreeNode(4);
        s.left.right = new TreeNode(5);
        s.right.left = new TreeNode(6);
        s.right.right = new TreeNode(7);
        String s1 = solution.Serialize(s);
        System.out.println(s1);
        /**************************************/
        String sstr = "1,2,#,5,#,#,3,6,#,#,#,";
        String str = "1 2 4 # # 5 # # 3 6 # # 7 # # ";
        TreeNode node = solution.Deserialize(str);
        System.out.println(PrintFromTopToBottom(node));
    }
}
/*
t = TreeNode(8)
t1 =TreeNode(6)
t2 = TreeNode(10)
t3 = TreeNode(5)
t4 =TreeNode(7)
t5 = TreeNode(9)
t6 = TreeNode(11)
t.left = t1
t.right = t2
t1.left = t3
t1.right = t4
t2.left = t5
t2.right = t6
print Solution().Serialize(t)
print Solution().Deserialize(Solution().Serialize(t))
 */

59ms

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Codec {
public String serialize(TreeNode root) 
{
    if(root == null) return "#";
    
    return "" + root.val + " " + serialize(root.left) + " " + serialize(root.right);
}


// Decodes your encoded data to tree.
public TreeNode deserialize(String data) 
{
    return build(new Scanner(data));
}

private TreeNode build(Scanner sc)
{
    if(!sc.hasNext()) return null;
    String tk = sc.next();
    if(tk.equals("#")) return null;
    
    TreeNode root = new TreeNode(Integer.parseInt(tk));
    root.left = build(sc);
    root.right = build(sc);
    
    return root;
}
}

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