solve(w12): 297. Serialize and Deserialize Binary Tree

Author: seungriyou

serialize-and-deserialize-binary-tree/seungriyou.py

@@ -0,0 +1,64 @@
+# https://leetcode.com/problems/serialize-and-deserialize-binary-tree/
+
+# Definition for a binary tree node.
+class TreeNode(object):
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+class Codec:
+
+    def serialize(self, root):
+        """Encodes a tree to a single string.
+
+        :type root: TreeNode
+        :rtype: str
+        """
+        res = []
+
+        def preorder_ser(node):
+            # base condition
+            if not node:
+                res.append("None")
+                return
+
+            # traversal
+            res.append(str(node.val))
+            preorder_ser(node.left)
+            preorder_ser(node.right)
+
+        preorder_ser(root)
+
+        return ",".join(res)
+
+    def deserialize(self, data):
+        """Decodes your encoded data to tree.
+
+        :type data: str
+        :rtype: TreeNode
+        """
+        from collections import deque
+
+        preorder_vals = deque(data.split(","))
+
+        def preorder_deser():
+            val = preorder_vals.popleft()
+
+            # base condition
+            if val == "None":
+                return None
+
+            # traversal
+            node = TreeNode(int(val))
+            node.left = preorder_deser()
+            node.right = preorder_deser()
+
+            return node
+
+        return preorder_deser()
+
+# Your Codec object will be instantiated and called as such:
+# ser = Codec()
+# deser = Codec()
+# ans = deser.deserialize(ser.serialize(root))