297.二叉树的序列化与反序列化,dfs,bfs

Author: linwt

leetcode_Java/DoneTitle.txt

@@ -103,6 +103,7 @@
 279. 完全平方数
 283. 移动零
 287. 寻找重复数
+297. 二叉树的序列化与反序列化
 300. 最长上升子序列
 301. 删除无效的括号
 303. 区域和检索 - 数组不可变

leetcode_Java/DoneType.txt

@@ -30,6 +30,7 @@
 199. 二叉树的右视图
 226. 翻转二叉树
 236. 二叉树的最近公共祖先
+297. 二叉树的序列化与反序列化
 437. 路径总和
 538. 把二叉搜索树转换为累加树
 543. 二叉树的直径

leetcode_Java/Solution0297.java

@@ -0,0 +1,106 @@
+// 297. 二叉树的序列化与反序列化
+
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+
+// Your Codec object will be instantiated and called as such:
+// Codec ser = new Codec();
+// Codec deser = new Codec();
+// TreeNode ans = deser.deserialize(ser.serialize(root));
+
+
+/*
+深度优先搜索：
+ */
+public class Codec {
+    public String serialize(TreeNode root) {
+        if (root == null) {
+            return "X,";
+        }
+        String leftSerialize = serialize(root.left);
+        String rightSerialize = serialize(root.right);
+        return root.val + "," + leftSerialize + rightSerialize;
+    }
+
+    public TreeNode deserialize(String data) {
+        String[] splits = data.split(",");
+        Deque<String> queue = new LinkedList<>(Arrays.asList(splits));
+        return build(queue);
+    }
+
+    private TreeNode build(Deque<String> queue) {
+        String s = queue.poll();
+        if (s.equals("X")) {
+            return null;
+        }
+        TreeNode node = new TreeNode(Integer.parseInt(s));
+        node.left = build(queue);
+        node.right = build(queue);
+        return node;
+    }
+}
+
+
+/*
+广度优先搜索：
+ */
+public class Codec {
+    public String serialize(TreeNode root) {
+        if (root == null) {
+            return "X,";
+        }
+        StringBuilder sb = new StringBuilder();
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.add(root);
+        while (!queue.isEmpty()) {
+            int size = queue.size();
+            while (size > 0) {
+                TreeNode node = queue.poll();
+                if (node != null) {
+                    sb.append(node.val + ",");
+                    queue.add(node.left);
+                    queue.add(node.right);
+                } else {
+                    sb.append("X,");
+                }
+                size--;
+            }
+        }
+        return sb.toString();
+    }
+
+    public TreeNode deserialize(String data) {
+        if (data.equals("X,")) {
+            return null;
+        }
+        String[] splits = data.split(",");
+        Deque<TreeNode> queue = new LinkedList<>();
+        TreeNode root = new TreeNode(Integer.parseInt(splits[0]));
+        queue.add(root);
+        int i = 1;
+        while (!queue.isEmpty()) {
+            TreeNode node = queue.poll();
+            if (!"X".equals(splits[i])) {
+                TreeNode left = new TreeNode(Integer.parseInt(splits[i]));
+                node.left = left;
+                queue.add(left);
+            }
+            i++;
+            if (!"X".equals(splits[i])) {
+                TreeNode right = new TreeNode(Integer.parseInt(splits[i]));
+                node.right = right;
+                queue.add(right);
+            }
+            i++;
+        }
+        return root;
+    }
+}