using System;

using System.Linq;

​

public class Program

{

    public class DiscountRule

    {

        public int BrandId

        {

            get;

            set;

        }

​

        public int CategoryId

        {

            get;

            set;

        }

​

        public bool BrandInclude

        {

            get;

            set;

        }

​

        public bool CategoryInclude

        {

            get;

            set;

        }

​

        public bool RuleClashes

        {

            get;

            set;

        }

​

        public bool CheckDiscountRuleClash(DiscountRule other)

        {

            if (this.CategoryId == other.CategoryId && this.BrandId == other.BrandId)

            {

                if (this.BrandInclude && this.CategoryInclude && !other.BrandInclude && !other.CategoryInclude)

                {

                    this.RuleClashes = true;

                    return true;

                }

                else if (!this.BrandInclude && !this.CategoryInclude && other.BrandInclude && other.CategoryInclude)

                {

                    this.RuleClashes = true;

                    return true;

                }

                else if (this.BrandInclude && !this.CategoryInclude && !other.BrandInclude && other.CategoryInclude)

                {

                    this.RuleClashes = true;

                    return true;

                }

                else if (!this.BrandInclude && this.CategoryInclude && other.BrandInclude && !other.CategoryInclude)

                {

                    this.RuleClashes = true;

                    return true;

                }

                else

                {

                    this.RuleClashes = false;

                    return false;

                }

            }

​

            return false;

        }

    }

​

    public static void Main()

    {

        var q =

            from categoryId in Enumerable.Range(0, 80)from brandId in Enumerable.Range(0, 80)select new DiscountRule

            {

            BrandId = brandId, CategoryId = categoryId, BrandInclude = true, CategoryInclude = true

            }

​

        ;

        var rules = q.ToList();

        rules.Add(new DiscountRule

        {

        BrandInclude = false

        }

​

        ); // This one would clash

        var sw1 = System.Diagnostics.Stopwatch.StartNew();

        var groups =

            from rule in rules

            group rule by new

            {

            rule.BrandId, rule.CategoryId

            }

​

                into g

                select new

                {

                g.Key, clashGroups = (

                    from i in g

                    group i by new

                    {

                    i.BrandInclude, i.CategoryInclude

                    }

​

                ).ToList()}

​

        ;

        foreach (var idGroup in groups.Where(g => g.clashGroups.Count() > 1))

        {

            //Console.WriteLine(idGroup.Key);

            foreach (var clashGroup in idGroup.clashGroups)

            {

                foreach (var rule in clashGroup)

                {

                    Console.WriteLine("CategoryId: {0}, BrandId: {1}, CategoryInclude: {2}, BrandInclude: {3}", rule.CategoryId, rule.BrandId, rule.CategoryInclude, rule.BrandInclude);

                    rule.RuleClashes = true;

                }

            }

        }

        sw1.Stop();

        Console.WriteLine("Fast method");

        Console.WriteLine(sw1.Elapsed);

        var sw2 = System.Diagnostics.Stopwatch.StartNew();

        var conflictingRules = rules.SelectMany(rule => 

    rules.Where(other => rule.CheckDiscountRuleClash(other))

    .Select(other=> new { rule, other }));

        foreach(var conflict in conflictingRules)

        {

            Console.WriteLine("CategoryId: {0}, BrandId: {1}, CategoryInclude: {2}, BrandInclude: {3}", conflict.rule.CategoryId, conflict.rule.BrandId, conflict.rule.CategoryInclude, conflict.rule.BrandInclude);

        }

        sw2.Stop();

        Console.WriteLine("Stupid method");

        Console.WriteLine(sw2.Elapsed);

        Console.WriteLine("Good one outperformed stupid one {0} times", (double)sw2.ElapsedMilliseconds / (double)sw2.ElapsedMilliseconds);

    }

}