如何从 C# 中的这个分层父子结构中找到任何项目

Question

如何从列表中找到任何项目，因为它是动态的，它可能在列表的任何 position 的父项或子项中，并且需要在子项列表为 0 时停止查找，下面是列表的 Model 和和分层父子结构示例

例子：-

父->子->子->子或父->子->子->子->子->子->子

public class Child
    {
        public string key { get; set; }
        public string title { get; set; }
        public string parent_Category { get; set; }
        public List<Child> children { get; set; }
    }

    public class Parent
    {
        public string key { get; set; }
        public string title { get; set; }
        public string parent_Category { get; set; }
        public List<Child> children { get; set; }
    }

Answer 1

您可以进行递归搜索，例如：

Child SearchChild(string title, Child c)
{
    if (c.title == title)
    {
        return c;
    }
    return SearchAmongChildren(title, c.children);
}

Child SearchAmongChildren(string title, List<Child> children)
{
    foreach (var c in children)
    {
        if (c.title == title)
        {
            return c;
        }

        if (c.children != null)
        {
            var _c = SearchAmongChildren(title, c.children);

            if (_c != null)
                return _c;
        }
    }

    return null;
}

然后，开始搜索：

var theChildThatIWant = SearchAmongChildren("the title that I want", parent.children);

var theChildThatIWant = SearchChild("the title that I want", child);

if (theChildThatIWant == null)
{
    throw new ChildNotFoundException("Sorry, the child that you're looking for is not available.");
}

Answer 2

您可以使用 BFS 或 DFS 搜索。

bool Exist(Parent parent, string key)
{
    if (parent.key == key) return true;

    if (parent.children == null) return false;
    var queue = new Queue<Child>(parent.children);
    while (queue.Any())
    {
        Child c = queue.Dequeue();
        bool match = c.key == key;
        if (match) return true;

        if (c.children == null) continue;
        foreach (Child grandChild in c.children)
        {
            queue.Enqueue(grandChild);
        }
    }

    return false;
}

// 测试场景

Parent parent1 = new Parent();
var result1 = Exist(parent1, "key-1");
Console.WriteLine($"Actual : {result1}, Expected : False");

Parent parent2 = new Parent { children = new List<Child> { new Child() { key = "key-1" }, new Child() { key = "key-2" } } };
var result2 = Exist(parent2, "key-2");
Console.WriteLine($"Actual : {result2}, Expected : True");

Parent parent3 = new Parent { children = new List<Child> { new Child() { key = "key-1" }, new Child() { key = "key-2", children = new List<Child> { new Child() { key = "key-5" } } } } };
var result3 = Exist(parent3, "key-5");
Console.WriteLine($"Actual : {result3}, Expected : True");

var result4 = Exist(parent3, "key-21323");
Console.WriteLine($"Actual : {result4}, Expected : False");