Question

我的文本文件是一个需要变成树的标签列表。

文件内容：

root
    node1
    node2
        node2_1
    node3
        node3_1
        node3_2
            node3_2_1
    node4

树应该看起来像：

                root          
    /     |       \         \
  node1 node2      node3     node4
          |      /       \
        node2_1 node3_1  node3_2
                           \
                          node3_2_1

我正在尝试创建一个递归方法来创建树，但不确定如何跟踪父和根。

Answer 1

假设你的Node类看起来像这样：

public class Node
{
    public Node(string value)
    {
        Value = value;
        Children = new List<Node>();
    }

    public string Value { get; }

    public List<Node> Children{ get; }
}

您可以尝试使用此方法获取树（假设您的输入与发布的一样，根是第一行）：

public Node GetTree(string filePath)
{
    string[] lines = System.IO.File.ReadAllLines(filePath);

    //if lines is empty the tree is null
    if(lines.Length == 0)
    {
        return null;
    }

    //create the root
    Node root = new Node(lines[0].Trim());

    //get the root leading white spaces length
    int rootWhiteSpaceLength = lines[0].TakeWhile(c => c=" ").Count();

    //Crete  a list to hold the nodes and their white space length
    List<Tuple<Node, int>> nodesAndLengths = new  List<Tuple<Node, int>>();

    //add the root to nodes list with it's white space length
    nodesAndLengths.Add(new Tuple<Node, int>(root, rootWhiteSpaceLength));       

    //iterate over the lines strating from index 1
    for (var i = 1; i < lines.Length, i++)
    {
        //create the node
        Node node = new Node(lines[i].Trim());

        //get the node leading white spaces length
        int nodeWhiteSpaceLength = lines[i].TakeWhile(c => c=" ").Count();

        //Check that is not another root
        if(nodeWhiteSpaceLength <= rootWhiteSpaceLength)
        {
            throw new Exception("There is more than one root");
        }

        //find the node parent in the nodes list using LINQ
        Node parent = nodesAndLengths.Last(nodeAndLength => nodeAndLength.Item2 < nodeWhiteSpaceLength).Item1;

        //Alternatively using while loop
        //int j = i - 1;
        //while(nodeWhiteSpaceLength >= nodesAndLengths[j].Item2)
        //{
            //j--;
        //}
        //Node parent=nodesAndLengths[j].Item1;

        //add the node to it's parent
        parent.Children.Add(node);

        //add the node to nodes list with it's white space length
        nodesAndLengths.Add(New Tuple<Node, int>(node, nodeWhiteSpaceLength));
    }

    return root; 
}

C＃选项卡式文本文件到树

1 个答案: