構建海峽

Question

這裏的具體名單是主類：

class GameStateNode: 
    ''' 
    A tree of possible states for a two-player, sequential move, zero-sum, 
    perfect-information game. 

    value: GameState -- the game state at the root of this tree 
    children: list -- all possible game states that can be reached from this 
    game state via one legal move in the game. children is None until grow 
    is called. 
    ''' 

    def __init__(self, game_state): 
     ''' (GameStateNode, GameState) -> NoneType 

     Initialize a new game state tree consisting of a single root node 
     that contains game_state. 
     ''' 
     self.value = game_state 
     self.children = [] 

這裏是我目前工作的功能：

def game_descriptions(root): 
    ''' (GameStateNode) -> list of str 

    Return a list containing a str describing each complete game that is 
    possible from the game stored at root. 

    Assume root is the root of a game state tree specifically for the game 
    Subtract Square. 

    >>> s = SubtractSquareState('p1', current_total = 6) 
    >>> root = GameStateNode(s) 
    >>> root.grow() 
    >>> game_descriptions(root) 
    ['p1:6 -> p2:2 -> p1:1 -> p2:0 = p1 wins!', 'p1:6 -> p2:5 -> p1:1 -> p2:0 = p1 wins!', 'p1:6 -> p2:5 -> p1:4 -> p2:0 = p1 wins!', 'p1:6 -> p2:5 -> p1:4 -> p2:3 -> p1:2 -> p2:1 -> p1:0 = p2 wins!'] 
    ''' 


def _build_paths(root, L = []): 
    ''' (GameStateNode) -> list of str ''' 
    if root.children: 
     for child in root.children: 
      a = abbreviated(root.value) 
      a += ' -> {}'.format(abbreviated(child.value)) 
      L.append(a) 
      _build_paths(child, L) 
    else: 
     pass 
    return L 

def abbreviated(s): 
    '''(GameState) -> str 

    Return an abbreviated str representation of SubtractSquareState s. 
    ''' 

    return "{}:{}".format(s.next_player, s.current_total) 

正如你可以在FCN game_descriptions看到我需要返回按照最後的勝利者的順序列出遊戲狀態。我目前的問題是使用fcn _build_paths。我希望它能夠在沒有獲勝者的情況下返回一個遊戲描述列表，因爲我將執行在fcn game_descriptions中獲勝的人。 我想這一點，例如：

>>> root = GameStateNode(SubtractSquareState('p1', current_total = 4)) 
>>> root.grow() 
>>> _build_paths(root) 
['p1:4 -> p2:0', 'p1:4 -> p2:3 -> p1:2 -> p2:1 -> p1:0'] 

相反，我得到這個：

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Answer 1

因爲你想要的字符串列表，您需要從列表中單獨建立一個字符串，表示當前路徑的所有字符串。您也可以使用它來指示起始點，這樣可以避免在每個路徑中列出每個節點兩次。

沒有所有的代碼，我不能對此進行測試，但我認爲這種一般形式的東西會工作：

_build_paths(root, abbreviated(root.value))