二叉树算法python实现：
1.添加节点
2.广度优先遍历
3.深度优先遍历：先序遍历，中序遍历，后序遍历

# -*- codding:utf-8 -*-class Node(object): """节点""" def __init__(self,item): self.elem = item self.lchild = None self.rchild = Noneclass Tree(object): """二叉树""" def __init__(self): self.root = None def add(self,item): node =Node(item) if self.root is None: self.root = node return queue = [self.root] while queue: cur_node = queue.pop(0) if cur_node.lchild is None: cur_node.lchild = node return else : queue.append(cur_node.lchild) if cur_node.rchild is None: cur_node.rchild = node return else : queue.append(cur_node.rchild) def bread_travel(self): """广度遍历""" if self.root is None: return queue = [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 pre_travel(self,node): """前序遍历""" if node is None: return print(node.elem,end = " ") self.pre_travel(node.lchild) self.pre_travel(node.rchild) def mid_travel(self,node): """中序遍历""" if node is None: return self.mid_travel(node.lchild) print(node.elem,end = " ") self.mid_travel(node.rchild) def post_travel(self,node): """后序遍历""" if node is None: return self.post_travel(node.lchild) self.post_travel(node.rchild) print(node.elem, end=" ")if __name__ == "__main__": tree = Tree() tree.add(0) tree.add(1) tree.add(2) tree.add(3) tree.add(4) tree.add(5) tree.add(6) tree.add(7) tree.add(8) tree.add(9) tree.bread_travel() print(" ") tree.pre_travel(tree.root) print(" ") tree.mid_travel(tree.root) print(" ") tree.post_travel(tree.root)# 0 1 2 3 4 5 6 7 8 9 层次遍历# 0 1 3 7 8 4 9 2 5 6 前序遍历# 7 3 8 1 9 4 0 5 2 6 中序遍历# 7 8 3 9 4 1 5 6 2 0 后序遍历