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73 lines
1.8 KiB
Python
73 lines
1.8 KiB
Python
"""
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File: binary_tree.py
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Created Time: 2021-12-11
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Author: Krahets (krahets@163.com)
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"""
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from collections import deque
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class TreeNode:
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"""Definition for a binary tree node"""
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def __init__(self, val: int = 0):
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self.val: int = val # 节点值
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self.height: int = 0 # 节点高度
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self.left: TreeNode | None = None # 左子节点引用
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self.right: TreeNode | None = None # 右子节点引用
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def list_to_tree(arr: list[int]) -> TreeNode | None:
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"""Generate a binary tree with a list"""
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if not arr:
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return None
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i: int = 0
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root = TreeNode(arr[0])
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queue: deque[TreeNode] = deque([root])
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while queue:
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node: TreeNode = queue.popleft()
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i += 1
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if i >= len(arr):
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break
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if arr[i] != None:
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node.left = TreeNode(arr[i])
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queue.append(node.left)
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i += 1
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if i >= len(arr):
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break
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if arr[i] != None:
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node.right = TreeNode(arr[i])
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queue.append(node.right)
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return root
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def tree_to_list(root: TreeNode | None) -> list[int]:
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"""Serialize a tree into an array"""
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if not root:
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return []
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queue: deque[TreeNode] = deque()
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queue.append(root)
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res: list[int] = []
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while queue:
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node: TreeNode | None = queue.popleft()
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if node:
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res.append(node.val)
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queue.append(node.left)
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queue.append(node.right)
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else:
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res.append(None)
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return res
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def get_tree_node(root: TreeNode | None, val: int) -> TreeNode | None:
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"""Get a tree node with specific value in a binary tree"""
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if not root:
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return
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if root.val == val:
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return root
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left: TreeNode | None = get_tree_node(root.left, val)
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right: TreeNode | None = get_tree_node(root.right, val)
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return left if left else right
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