用python实现树

用python实现树

class Node(object):
   def __init__(self,item):
        self.elem=item
        self.lchild=None
        self.rchild=None

	
	
class Tree(object):
    def __init__(self):
        self.root=None
    def add(self,item):
        node=Node(item)
        if self.root==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 breadth_travel(self):
        #广度优先遍历
        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)

	#深度优先
    def preorder(self,node):
        #先序遍历
        if node is None:
            return
        print(node.elem,end='')
        self.preorder(node.lchild)
        self.preorder(node.rchild)

    def inorder(self,node):
        #中序遍历
        if node is None:
            return
        self.preorder(node.lchild)
        print(node.elem, end='')
        self.preorder(node.rchild)


    def postorder(self,node):
        #后序遍历
        if node is None:
            return
        self.preorder(node.lchild)
        self.preorder(node.rchild)
        print(node.elem, end='')

if __name__ == '__main__':
    tree=Tree()
    tree.add(1)
    tree.add(2)
    tree.add(3)
    tree.add(4)
    tree.add(5)
    tree.breadth_travel()
    print(' ')
    tree.preorder(tree.root)
    print(' ')
    tree.inorder(tree.root)
    print(' ')
    tree.postorder(tree.root)