using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace ConsoleApp1

{

    public class Program

    {

        public static void Main()

        {

​

            Load load = GetLoad();

            foreach (var billTo in load.billTos)

            {

                var customers = load.billToStops

                    .Where(b => b.billToSeqNum == billTo.seqNum)

                    .Join(load.customerStops, bs => bs.stopSeqNum, cs => cs.stopSeqNum, (bs, cs) => cs)

                    .Join(load.customers, cs => cs.custSeqNum, c => c.custSeqNum, (cs, c) => c)

                    .Distinct();

                //Alternate Approach 1

                //var billToStops = load.billToStops.Where(x => x.billToSeqNum == billTo.seqNum);

                //

                //var customerStops = billToStops.SelectMany(billToStop =>

                //{

                //    return load.customerStops.Where(

                //        customerStop => customerStop.stopSeqNum == billToStop.stopSeqNum);

                //}).Distinct();

                //

                //var customers = customerStops.SelectMany(custStop =>

                //{

                //    return load.customers.Where(cust => custStop.custSeqNum == cust.custSeqNum);

                //}).Distinct();

​

                //Alternate Approach 2

                //var customers = load.billToStops.Where(s => s.stopSeqNum == billTo.seqNum)

                //    .SelectMany(billToStop =>

                //    {

                //        return load.customerStops.Where(cs => cs.stopSeqNum == billToStop.stopSeqNum);

                //    })

                //    .SelectMany(custStop =>

                //    {

                //        return load.customers.Where(cust => custStop.custSeqNum == cust.custSeqNum);

                //    })

                //    .Distinct();

​

                Console.WriteLine("Bill To: " + billTo.seqNum);

                foreach (var cust in customers)

                {

                    Console.WriteLine("Customer Code: " + cust.CCode);

                }

            }

​

        }

        //DATA

        public class Load

        {

            public List<BillTo> billTos { get; set; }

            public List<BillToStop> billToStops { get; set; }

            public List<CustomerStop> customerStops { get; set; }

            public List<Customer> customers { get; set; }

        }

​

        public class BillTo

        {

            public string seqNum { get; set; }

        }

​

        public class BillToStop

        {

            public string billToSeqNum { get; set; }

            public string stopSeqNum { get; set; }

        }

​

        public class CustomerStop

        {

            public string stopSeqNum { get; set; }

            public string custSeqNum { get; set; }

        }

​

        public class Customer

        {

            public string custSeqNum { get; set; }

            public string CCode { get; set; }

        }

​

        public static Load GetLoad()

        {

            var load = new Load()

            {

                billTos = new List<BillTo>(){

                new BillTo(){

                    seqNum = "B1"

                },

                new BillTo(){

                    seqNum = "B2"

                }

            },

                billToStops = new List<BillToStop>(){

                new BillToStop(){

                    billToSeqNum = "B1",

                    stopSeqNum = "S1"

                },

                new BillToStop(){

                    billToSeqNum = "B1",

                    stopSeqNum = "S1"

                },

                new BillToStop(){

                    billToSeqNum = "B2",

                    stopSeqNum = "S3"

                },

                new BillToStop(){

                    billToSeqNum = "B2",

                    stopSeqNum = "S4"

                }

            },

                customerStops = new List<CustomerStop>(){

                new CustomerStop(){

                    stopSeqNum = "S1",

                    custSeqNum = "C1"

                },

                new CustomerStop(){

                    stopSeqNum = "S1",

                    custSeqNum = "C2"

                },

                new CustomerStop(){

                    stopSeqNum = "S2",

                    custSeqNum = "C1"

                },

                new CustomerStop(){

                    stopSeqNum = "S2",

                    custSeqNum = "C2"

                },

                new CustomerStop(){

                    stopSeqNum = "S3",

                    custSeqNum = "C1"

                },

                new CustomerStop(){

                    stopSeqNum = "S3",

                    custSeqNum = "C2"

                },

                new CustomerStop(){

                    stopSeqNum = "S4",

                    custSeqNum = "C1"

                },

                new CustomerStop(){

                    stopSeqNum = "S4",

                    custSeqNum = "C3"

                }

            },

                customers = new List<Customer>(){

                new Customer(){

                    custSeqNum = "C1",

                    CCode = "C10000"

                },

                new Customer(){

                    custSeqNum = "C2",

                    CCode = "C20000"

                },

                    new Customer(){

                        custSeqNum = "C3",

                        CCode = "C30000"

                }

            }

            };

            return load;

        }

    }

}

​

​