data_structures_and_algorithms/binary_tree at master · Rswcf/data_structures_and_algorithms · GitHub

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class Node(object):

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


class Tree(object):
    '''Binary Tree'''

    def __init__(self):
        self.root = None

    def add(self, item):
        node = Node(item)
        if self.root is None:
            self.root = node
        else:
            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 preorder(self, node):
        if node is None:
            return
        print(node.elem, end=' ')

        self.preorder(node.lchild)
        self.preorder(node.rchild)

    def inorder(self, node):
        if node is None:
            return

        self.inorder(node.lchild)
        print(node.elem, end=' ')
        self.inorder(node.rchild)

    def postorder(self, node):
        if node is None:
            return

        self.postorder(node.lchild)

        self.postorder(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.add(6)
    tree.add(7)
    tree.add(8)
    tree.add(9)
    tree.breadth_travel()
    print('')
    tree.preorder(tree.root)
    print('')
    tree.inorder(tree.root)
    print('')
    tree.postorder(tree.root)
    print('')