Construct Binary Tree from Preorder and Postorder Traversal

lc889.py

@@ -0,0 +1,34 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def constructFromPrePost(self, pre, post):
+        """
+        :type pre: List[int]
+        :type post: List[int]
+        :rtype: TreeNode
+        """
+
+        if not pre:
+            return None
+        root=TreeNode(pre[0])
+
+        if len(pre)>1:
+            i=post.index(pre[1])
+            root.left=self.constructFromPrePost(pre[1:(i+2)],post[:(i+1)])
+            root.right=self.constructFromPrePost(pre[(i+2):],post[(i+1):-1])
+
+        return root
+
+
+
+
+s=Solution()
+pre = [1,2,4,5,3,6,7]
+post = [4,5,2,6,7,3,1]
+
+print(s.constructFromPrePost(pre,post))