mirror of
https://github.com/autistic-symposium/master-algorithms-py.git
synced 2025-04-29 20:26:07 -04:00
Update and rename bt_construction_inorder_postorder.py to bt_construct_inorder_postorder.py
This commit is contained in:
parent
dd98393aa4
commit
b61c58b158
25
trees/bt_construct_inorder_postorder.py
Normal file
25
trees/bt_construct_inorder_postorder.py
Normal file
@ -0,0 +1,25 @@
|
|||||||
|
#!/usr/bin/env python3
|
||||||
|
# -*- coding: utf-8 -*-
|
||||||
|
# author: bt3gl
|
||||||
|
|
||||||
|
|
||||||
|
def build_tree(left, right, index_map):
|
||||||
|
|
||||||
|
if left > right:
|
||||||
|
return None
|
||||||
|
|
||||||
|
root = Node(postorder.pop()) # this order change from preorder
|
||||||
|
index_here = index_map[root.val]
|
||||||
|
|
||||||
|
root.right = build_tree(index_here + 1, right, index_map) # this order change from preorder
|
||||||
|
root.left = build_tree(left, index_here - 1, index_map)
|
||||||
|
|
||||||
|
return root
|
||||||
|
|
||||||
|
|
||||||
|
def build_tree(inorder, postorder) -> Optional[Node]:
|
||||||
|
|
||||||
|
index_map = {val: i for i, value in enumerate(inorder)}
|
||||||
|
|
||||||
|
return fill_tree(0, len(inorder) - 1, index_map)
|
||||||
|
|
@ -1,29 +0,0 @@
|
|||||||
#!/usr/bin/env python3
|
|
||||||
# -*- coding: utf-8 -*-
|
|
||||||
# author: bt3gl
|
|
||||||
# Given two integer arrays inorder and postorder where inorder is the inorder
|
|
||||||
# traversal of a binary tree and postorder is the postorder traversal of the
|
|
||||||
# same tree, construct and return the binary tree.
|
|
||||||
|
|
||||||
|
|
||||||
def fill_tree(i_left, i_right, inorder_map):
|
|
||||||
|
|
||||||
if i_left > i_right:
|
|
||||||
return None
|
|
||||||
|
|
||||||
val = postorder.pop()
|
|
||||||
root = TreeNode(val)
|
|
||||||
|
|
||||||
index_here = inorder_map[val]
|
|
||||||
|
|
||||||
root.right = fill_tree(index_here + 1, i_right, inorder_map)
|
|
||||||
root.left = fill_tree(i_left, index_here - 1, inorder_map)
|
|
||||||
|
|
||||||
return root
|
|
||||||
|
|
||||||
|
|
||||||
def build_tree(inorder: list[int], postorder: list[int]) -> Optional[TreeNode]:
|
|
||||||
|
|
||||||
inorder_map = {val: index for index, val in enumerate(inorder)}
|
|
||||||
return fill_tree(0, len(inorder) - 1, inorder_map)
|
|
||||||
|
|
Loading…
x
Reference in New Issue
Block a user