Python数据结构与算法06——树与树算法

二叉树

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

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==None:
                cur_node.lchild=node
                return
            else:
                queue.append(cur_node.lchild)
            if cur_node.rchild==None:
                cur_node.rchild=node
                return
            else:
                queue.append(cur_node.rchild)
    def breadth_travel(self):
        if self.root==None:
            print('NULL')
            return
        queue=[self.root]
        while queue:
            cur_node = queue.pop(0)
            print(cur_node.val, end=' ')
            if cur_node.lchild!=None:
                queue.append(cur_node.lchild)
            if cur_node.rchild!=None:
                queue.append(cur_node.rchild)

    def preorder_travel(self,node):
        if node==None:
            return
        print(node.val,end=' ')
        self.preorder_travel(node.lchild)
        self.preorder_travel(node.rchild)

    def inorder_travel(self,node):
        if node==None:
            return
        self.inorder_travel(node.lchild)
        print(node.val, end=' ')
        self.inorder_travel(node.rchild)
    def postorder_travel(self,node):
        if node==None:
            return
        self.postorder_travel(node.lchild)
        self.postorder_travel(node.rchild)
        print(node.val, end=' ')




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.breadth_travel()
print(' ')
tree.preorder_travel(tree.root)
print(' ')
tree.inorder_travel(tree.root)
print(' ')
tree.postorder_travel(tree.root)