Done Tree 2

Problem1.py

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+# Construct Binary Tree from Inorder and Postorder Traversal
+
+# 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:
+    rootIndex = 0
+    def buildTree(self, inorder: List[int], postorder: List[int]) -> Optional[TreeNode]:
+        self.rootIndex = len(postorder)-1
+        inOrderIndexMap = {}
+
+        for i in range(0,len(inorder)):
+            inOrderIndexMap[i] = inOrderIndexMap[i]
+
+        return self.helper(inOrderIndexMap,postorder,0,len(inorder)-1)
+
+
+    def helper(self, inOrderIndexMap, postorder, inOrderLeftIndex, inorderRightIndex):
+        if inOrderLeftIndex>inorderRightIndex:
+            return None
+        rootVal = postorder[self.rootIndex]
+        self.rootIndex-=1
+
+        inOrderRootValIndex = inOrderIndexMap[rootVal]
+        rootNode = TreeNode(rootVal)
+        rootNode.right = self.helper(inOrderIndexMap,postorder,inOrderRootValIndex+1,inorderRightIndex)
+
+        rootNode.left = self.helper(inOrderIndexMap,postorder,inOrderLeftIndex,inOrderRootValIndex-1)
+
+        return rootNode

Problem2.py

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+#Sum Root to Leaf Numbers
+
+#Time complexity -> On  -> Iterating throguh each node once
+#Space complexity -> Oh ->Stack for the tree depyh
+# 
+# Iterate over the left and right nodes and maintain a current number, on moving to child node multiply the current number
+# by 10 and add the root value to the current number. Once at leaf add to the number tot he result  
+
+# 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 sumNumbers(self, root: Optional[TreeNode]) -> int:
+        result = 0
+        currentNumber = 0
+        return self.helper(root,currentNumber*10, result)
+
+
+    def helper(self,root,currentNumber, result ):
+
+        currentNumber = currentNumber + root.val
+
+        if root.left !=None:
+            result = self.helper(root.left, currentNumber*10, result)
+
+        if root.right != None:
+            result = self.helper(root.right, currentNumber*10, result)
+
+        if root.left == None and root.right == None:
+            result+=currentNumber
+        return result