节点: class TreeNode{int val;TreeNode left;TreeNode right;TreeNode(int val){this.val = val;}} 前序: public List<Integer> preorderTraversal(TreeNode root) {List<Integer> result = new ArrayList<>
event系统的核心至少满足: 1.存放事件的容器,可对事件添加删除 2.事件的触发fire 上代码. class Event(list):def __call__(self, *args, **kwargs):for f in self:f(*args, **kwargs)def f(arg): print 'execute with arg',arge = Event(