树 --> object

面向对象设计方法

def increment(n):return n+1def square(n):return n**2class Node:def __init__(self, parent, action, answer):self.parent = parentself.action = actionself.answer = answerdef path(self):if self.parent == None:return [(self.action, self.answer)]else:return self.parent.path() + [(self.action, self.answer)]def findSequence3(initial, goal):q = [Node(None, None, 1)]while q:parent = q.pop(0)for (a, r) in [('increment', increment), ('square', square)]:newNode = Node(parent, a, r(parent.answer))if newNode.answer == goal:return newNode.path()else:q.append(newNode)return Nonedef testFindSequence3():answer = findSequence3(1,100)print('answer =',answer)