Question

class Node(object):
    def __init__(self,value):
        self.value=value
        self.left=None
        self.right=None

class Tree(object):
    def __init__(self,values):
        length=len(values)
        node=[]
        for x in range(length):
            node.append(Node(values[x]))
        for x in range(length):
            if 2*x+1 < length:
                node[x].left = node[2*x+1]
            if 2*x+2 < length:
                node[x].right = node[2*x+2]
        if node[0] != None:
            self.root = node[0]
        else:
            self.root = None

    def DFS(self,node,obj):
        if node == None or node.value == obj:
            return node
        else:
            self.DFS(node.left,obj)
            self.DFS(node.right,obj)

def main():
    obj = raw_input("Please input a number you want to search: ")
    tree = Tree(range(100))
    node = tree.DFS(tree.root,obj)
    if node.value == obj:
        print "I've done it!"

if __name__ == "__main__":
    main()

嗨，我是python和这个平台的新手。我想在我的python＆＃39; Tree＆＃39;中实现DFS。但是shell说“树”＃39;对象没有属性＆＃39; DFS＆＃39;。但是，DFS在我的代码中明确定义。谁能帮我这个？非常感谢提前！

Answer 1

执行您的代码，我收到一条不同的错误消息：

    if node.value == obj:
AttributeError: 'NoneType' object has no attribute 'value'

此错误消息是因为Tree.DFS()实际上并不总是显式返回任何内容（因此会返回None），并且None没有value属性

Answer 2

我无法看到您说的问题。我从这里得到一个错误：

def DFS(self,node,obj):
    if node == None or node.value == obj:
        return node

AttributeError: 'NoneType' object has no attribute 'value'

当node == None返回None时，value不能/不具有$http.get('json.php').then(function(response){ // Place a debugger statement here to see if it's successful $scope.myData = response.data.bands; }, function(error) { // No breakpoint needed as you'll see the error in the console window console.error(error); });属性。

对象没有属性

2 个答案: