将包含多对多关系项的List<string>转换为一对多关系

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<string> relationships = new List<string>
        {
            "A,B",
            "A,C",
            "B,D",
            "C,D",
            "C,E"
        };

        Dictionary<string, List<string>> oneToManyRelationships = new Dictionary<string, List<string>>();

        foreach (string relationship in relationships)
        {
            string[] items = relationship.Split(',');

            string key = items[0];
            string value = items[1];

            if (oneToManyRelationships.ContainsKey(key))
            {
                oneToManyRelationships[key].Add(value);
            }
            else
            {
                oneToManyRelationships[key] = new List<string> { value };
            }
        }

        foreach (KeyValuePair<string, List<string>> pair in oneToManyRelationships)
        {
            Console.WriteLine(pair.Key + " -> " + string.Join(",", pair.Value));
        }
    }
}