使用linq将列表转换为字典,而不必担心重复

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        List<string> items = new List<string> { "apple", "banana", "cherry", "date", "fig", "grape", "apple" };

        Dictionary<string, string> uniqueItems = items
            .Select((item, index) => new { Item = item, Index = index })
            .GroupBy(x => x.Item)
            .ToDictionary(g => g.Key, g => g.First().Item);

        foreach (KeyValuePair<string, string> pair in uniqueItems)
        {
            Console.WriteLine("Key: {0}, Value: {1}", pair.Key, pair.Value);
        }
    }
}