二叉树

class Node(object):""""""def __init__(self, item):self.elem = itemself.lchild = Noneself.rchild = Noneclass Tree(object):"""二叉树"""def __init__(self):self.root = Nonedef add(self, item):node = Node(item)if self.root is None:self.root = nodereturnqueue = [self.root]while queue:cur_node = queue.pop(0)if cur_node.lchild is None:cur_node.lchild = nodereturnelse:queue.append(cur_node.lchild)if cur_node.rchild is None:cur_node.rchild = nodereturnelse:queue.append(cur_node.rchild)

二叉树三种遍历

 def breadth_travel(self):"""广度遍历"""if self.root is None:returnqueue = [self.root]while queue:cur_node = queue.pop(0)print(cur_node.elem, end=" ")if cur_node.lchild is not None:queue.append(cur_node.lchild)if cur_node.rchild is not None:queue.append(cur_node.rchild)def preorder(self, node):"""先序遍历"""if node is None:returnprint(node.elem, end=" ")self.preorder(node.lchild)self.preorder(node.rchild)def inorder(self, node):"""中序遍历"""if node is None:returnself.inorder(node.lchild)print(node.elem, end=" ")self.inorder(node.rchild)def postorder(self, node):"""后序遍历"""if node is None:returnself.postorder(node.lchild)self.postorder(node.rchild)print(node.elem, end=" ")

二叉树知中及先或后序，求二叉树