Merge pull request #3195 from thesouldev/main

Create: 0106-construct-binary-tree-from-inorder-and-postorder-traversal.py

Author: MHamiid

python/0106-construct-binary-tree-from-inorder-and-postorder-traversal.py

@@ -0,0 +1,25 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def buildTree(self, inorder: List[int], postorder: List[int]) -> Optional[TreeNode]:
+        def buildTreeHelper(left, right):
+            if left > right:
+                return None
+
+            rootVal = postorder.pop()
+            rootNode = TreeNode(rootVal)
+
+            idx = inorderIndexMap[rootVal]
+            rootNode.right = buildTreeHelper(idx + 1, right)
+            rootNode.left = buildTreeHelper(left, idx - 1)
+            return rootNode
+
+        inorderIndexMap = {}
+        for (i, val) in enumerate(inorder):
+            inorderIndexMap[val] = i
+
+        return buildTreeHelper(0, len(postorder) - 1)