过滤和计算方案？

Question

给定以下对象数组：

[
{ Code="X", Price=".01", DateTime="12/01/2017 08:00pm" },
{ Code="Y", Price=".02", DateTime="12/01/2017 05:40pm" },
{ Code="X", Price=".03", DateTime="12/01/2017 02:00pm" }
]

什么是优雅的方式？：

1. 获得Code X的最早价格
2. 确定新提供的小数是否在该价格的+/- 10％范围内？

Answer 1

嗯，这似乎很简单......

using System;
using System.Diagnostics;
using System.Linq;

namespace Test {
    class Program {
        static void Main(string[] args) {
            var items = new[] {
                new { Code= "X", Price=0.01, DateTime="12/01/2017 08:00pm" },
                new { Code ="Y", Price=0.02, DateTime="12/01/2017 05:40pm" },
                new { Code ="X", Price=0.03, DateTime="12/01/2017 02:00pm" }
            };
            var newItem = new { Code = "X", Price = 0.04, DateTime = "12/01/2017 09:00pm" };

            var xItems = items.Where(x => x.Code == "X");
            var minDateTime = xItems.Select(x => x.DateTime).Min();
            Debug.WriteLine($"minDateTime={minDateTime}");

            var minItem = xItems.Where(x => x.DateTime == minDateTime).Single();
            Debug.WriteLine($"minItem.Price={minItem.Price}");

            bool withinPercent = Math.Abs(newItem.Price / minItem.Price - 1.0) < 0.1;
            Debug.WriteLine($"newItem within 10%={withinPercent}");
        }
    }
}

这输出......

minDateTime=12/01/2017 02:00pm
minItem.Price=0.03
newItem within 10%=False