二叉树(python)
Posted muzinan110
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# -*- coding: utf-8 -*- from collections import deque class Queue(object): def __init__(self): self._items = deque() def append(self, value): return self._items.append(value) def pop(self): return self._items.popleft() def empty(self): return len(self._items) == 0 class Stack(object): def __init__(self): self._items = deque() def push(self, value): return self._items.append(value) def pop(self): return self._items.pop() def empty(self): return len(self._items) == 0 class BinTreeNode(object): def __init__(self, data, left=None, right=None): self.data, self.left, self.right = data, left, right class BinTree(object): def __init__(self, root=None): self.root = root @classmethod def build_from(cls, node_list): """build_from :param node_list: ‘data‘: ‘A‘, ‘left‘: None, ‘right‘: None, ‘is_root‘: False """ node_dict = for node_data in node_list: data = node_data[‘data‘] node_dict[data] = BinTreeNode(data) for node_data in node_list: data = node_data[‘data‘] node = node_dict[data] if node_data[‘is_root‘]: root = node node.left = node_dict.get(node_data[‘left‘]) node.right = node_dict.get(node_data[‘right‘]) return cls(root) def preorder_trav(self, subtree): if subtree is not None: print(subtree.data) self.preorder_trav(subtree.left) self.preorder_trav(subtree.right) def preorder_trav_use_stack(self, subtree): s = Stack() if subtree: s.push(subtree) while not s.empty(): top_node = s.pop() print(top_node.data) if top_node.right: s.push(top_node.right) if top_node.left: s.push(top_node.left) def inorder_trav(self, subtree): if subtree is not None: self.inorder_trav(subtree.left) print(subtree.data) self.inorder_trav(subtree.right) def yield_inorder(self, subtree): if subtree: yield from self.inorder(subtree.left) yield subtree.val yield from self.inorder(subtree.right) def reverse(self, subtree): if subtree is not None: subtree.left, subtree.right = subtree.right, subtree.left self.reverse(subtree.left) self.reverse(subtree.right) def layer_trav(self, subtree): cur_nodes = [subtree] next_nodes = [] while cur_nodes or next_nodes: for node in cur_nodes: print(node.data) if node.left: next_nodes.append(node.left) if node.right: next_nodes.append(node.right) cur_nodes = next_nodes next_nodes = [] def layer_trav_use_queue(self, subtree): q = Queue() q.append(subtree) while not q.empty(): cur_node = q.pop() print(cur_node.data) if cur_node.left: q.append(cur_node.left) if cur_node.right: q.append(cur_node.right) node_list = [ ‘data‘: ‘A‘, ‘left‘: ‘B‘, ‘right‘: ‘C‘, ‘is_root‘: True, ‘data‘: ‘B‘, ‘left‘: ‘D‘, ‘right‘: ‘E‘, ‘is_root‘: False, ‘data‘: ‘D‘, ‘left‘: None, ‘right‘: None, ‘is_root‘: False, ‘data‘: ‘E‘, ‘left‘: ‘H‘, ‘right‘: None, ‘is_root‘: False, ‘data‘: ‘H‘, ‘left‘: None, ‘right‘: None, ‘is_root‘: False, ‘data‘: ‘C‘, ‘left‘: ‘F‘, ‘right‘: ‘G‘, ‘is_root‘: False, ‘data‘: ‘F‘, ‘left‘: None, ‘right‘: None, ‘is_root‘: False, ‘data‘: ‘G‘, ‘left‘: ‘I‘, ‘right‘: ‘J‘, ‘is_root‘: False, ‘data‘: ‘I‘, ‘left‘: None, ‘right‘: None, ‘is_root‘: False, ‘data‘: ‘J‘, ‘left‘: None, ‘right‘: None, ‘is_root‘: False, ] btree = BinTree.build_from(node_list) print(‘====先序遍历=====‘) btree.preorder_trav(btree.root) print(‘====使用 stack 实现先序遍历=====‘) btree.preorder_trav_use_stack(btree.root) print(‘====层序遍历=====‘) btree.layer_trav(btree.root) print(‘====用队列层序遍历=====‘) btree.layer_trav_use_queue(btree.root) btree.reverse(btree.root) print(‘====反转之后的结果=====‘) btree.preorder_trav(btree.root)
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