Add 297

Author: ChienkuChen

src/_297/297.serialize-and-deserialize-binary-tree.java

@@ -0,0 +1,58 @@
+package _297;
+
+import datastructure.TreeNode;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.Queue;
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ * int val;
+ * TreeNode left;
+ * TreeNode right;
+ * TreeNode(int x) { val = x; }
+ * }
+ */
+class Codec {
+
+    // Encodes a tree to a single string.
+    public String serialize(TreeNode root) {
+        if (root == null)
+            return "null";
+
+        return root.val + "," + serialize(root.left) + "," + serialize(root.right);
+    }
+
+
+    // Decodes your encoded data to tree.
+    public TreeNode deserialize(String data) {
+        Queue<String> list = new LinkedList<>(Arrays.asList(data.split(",")));
+        return deserializeHelp(list);
+    }
+
+    private TreeNode deserializeHelp(Queue<String> queue) {
+        if (queue.size() == 0)
+            return null;
+
+        String s = queue.poll();
+        if (s.equals("null"))
+            return null;
+
+        TreeNode root = new TreeNode(Integer.valueOf(s));
+        root.left = deserializeHelp(queue);
+        root.right = deserializeHelp(queue);
+
+        return root;
+    }
+
+    public static void main(String[] args) {
+        final Codec codec = new Codec();
+        System.out.println(codec.serialize(codec.deserialize("1,2,null,null,3,4,5")));
+    }
+}
+
+// Your Codec object will be instantiated and called as such:
+// Codec codec = new Codec();
+// codec.deserialize(codec.serialize(root));