使用LINQ对列表项进行GROUPBY和SUM

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

public class Item
{
    public string Category { get; set; }
    public int Value { get; set; }
}

public class Program
{
    public static void Main()
    {
        // 创建包含数据的列表
        List<Item> items = new List<Item>
        {
            new Item { Category = "A", Value = 10 },
            new Item { Category = "B", Value = 20 },
            new Item { Category = "A", Value = 30 },
            new Item { Category = "B", Value = 40 },
            new Item { Category = "A", Value = 50 }
        };

        // 使用LINQ进行GROUP BY和SUM操作
        var result = items
            .GroupBy(x => x.Category) // 按Category分组
            .Select(g => new { Category = g.Key, Total = g.Sum(x => x.Value) }) // 计算每个分组的总和
            .ToList(); // 转换为列表

        // 输出结果
        foreach (var item in result)
        {
            Console.WriteLine($"Category: {item.Category}, Total: {item.Total}");
        }
    }
}