1. 用一个一维数组保存二叉树结点。 2. 实现二叉树节点的返回左孩子，返回右孩子，添加结点 3. 层序遍历二叉树。 -1. With a one-dimensional array to preserve binary tree nodes. 2. The realization of binary tree nodes to return to the left child, return the right child, add the node 3. Binary tree