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出于某种原因，我似乎无法让“查找”方法起作用。我认为这与范围界定问题有关...... root.val 似乎没有在全球范围内更新。我收到一条错误消息，说 AtributeError: 'int' object has no attribute 'val' 这是我目前的代码：

class BinaryNode:
    def __init__(self, v):
        self.val = v
        self.leftChild = None
        self.rightChild = None
    def get(self):
        return self.val
    def set(self, v):
        self.val = v
    def getChildren(self):
        children = []
        if self.leftChild != None:
            children.append(self.leftChild)
        if self.rightChild != None:
            children.append(self.rightChild)
        return children

class Tree:
    def __init__(self):
        self.root = None
    def setRoot(self, node):
        self.root = node
    def size(self):
        if self.root == None:
            return 0
    def subtreeSize(node):
        return 1 + sum(subtreeSize(c) for c in node.getChildren())
        return subtreeSize(self.root)

class BinarySearchTree(Tree):
    def insert(self, val):
        self.insertNode(self.root, val)

    def insertNode(self, node, val):
        if node is None:
            self.setRoot(BinaryNode(val))
        elif val <= node.val:
            node.leftChild = insertNode(BinaryNode(val), val)
        elif val > node.val:
            node.rightChild = insertNode(BinaryNode(val), val)
        else:
            node.val = val


    def find(self, val):
        self.findNode(self.root, val)

    def findNode(self, node, val):
        if node is None:
            return False
        elif val == node.val:
            return True
        elif val < node.val:
            self.findNode(val, node.leftChild)
        else:
            self.findNode(val, node.rightChild)


if __name__ == "__main__":
    btree = BinarySearchTree()
    vals = [5]
    for v in vals:
        btree.insert(v)
    tests = [8, 5]
    for t in tests:
        print "find(%i) = %s" % (t, ("True" if btree.find(t) else "False"))
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2 回答 2

5

你的方法有两个问题findNode()：

  1. 递归调用时交换了nodeand参数。val这会导致您的代码尝试查找.val整数值而不是节点。

  2. 您忘记返回递归调用结果。

修正方法：

def find(self, val):
    return self.findNode(self.root, val)

def findNode(self, node, val):
    if node is None:
        return False
    elif val == node.val:
        return True
    elif val < node.val:
        return self.findNode(node.leftChild, val)
    else:
        return self.findNode(node.rightChild, val)

你的下一个问题是你的insertNode方法；您尝试在insertNode()其中调用全局函数；那可能应该是self.insertNode()。但是，该方法没有返回值，因此您最终设置了node.leftChildor 。node.rightChildNone

您只想将插入点的搜索交给递归调用，无需使用返回值：

def insert(self, val):
    if self.root is None:
        self.setRoot(BinaryNode(val))
    else:
        self.insertNode(self.root, val)

def insertNode(self, node, val):
    if val <= node.val:
        if node.leftChild:
            self.insertNode(node.leftChild, val)
        else:
            node.leftChild = BinaryNode(val)
    elif val > node.val:
        if node.rightChild:
            self.insertNode(node.rightChild, val)
        else:
            node.rightChild = BinaryNode(val)

通过这些更改，您的简单测试将打印：

find(8) = False
find(5) = True
于 2013-04-12T08:56:02.100 回答
0

一个问题findNode()是您缺少return陈述。这

    elif val < node.val:
        self.findNode(val, node.leftChild)
    else:
        self.findNode(val, node.rightChild)

应该读

    elif val < node.val:
        return self.findNode(val, node.leftChild)
    else:
        return self.findNode(val, node.rightChild)

您在insertNode().

于 2013-04-12T08:52:52.127 回答