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

public class Tree<TreeNode> : IEnumerable<TreeNode> where TreeNode : IComparable<TreeNode> {
    public Tree(TreeNode nodeValue) {
        this.NodeData = nodeValue;
        this.LeftTree = null;
        this.RightTree = null;
    }

    public void Insert(TreeNode newItem) {
        TreeNode currentNodeValue = this.NodeData;
        if (currentNodeValue.CompareTo(newItem) > 0) {
            if (this.LeftTree == null) {
                this.LeftTree = new Tree<TreeNode>(newItem);
            } else {
                this.LeftTree.Insert(newItem);
            }
        } else {
            if (this.RightTree == null) {
                this.RightTree = new Tree<TreeNode>(newItem);
            } else {
                this.RightTree.Insert(newItem);
            }
        }
    }

    public void WalkTree() {
        if (this.LeftTree != null) {
            this.LeftTree.WalkTree();
        }

        Console.WriteLine(this.NodeData.ToString());

        if (this.RightTree != null) {
            this.RightTree.WalkTree();
        }
    }

    public TreeNode NodeData { get; set; }
    public Tree<TreeNode> LeftTree { get; set; }
    public Tree<TreeNode> RightTree { get; set; }


    IEnumerator<TreeNode> IEnumerable<TreeNode>.GetEnumerator() {
        if (this.LeftTree != null) {
            foreach (TreeNode item in this.LeftTree) {
                yield return item;
            }
        }

        yield return this.NodeData;

        if (this.RightTree != null) {
            foreach (TreeNode item in this.RightTree) {
                yield return item;
            }
        }
    }
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
        throw new NotImplementedException();
    }
}

class Employee : IComparable<Employee> {
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Department { get; set; }
    public int Id { get; set; }

    public override string ToString() {
        return String.Format("Id: {0}, Name: {1} {2}, Dept: {3}", this.Id, this.FirstName, this.LastName, this.Department);
    }
    int IComparable<Employee>.CompareTo(Employee other) {
        if (other == null)
            return 1;

        if (this.Id > other.Id)
            return 1;

        if (this.Id < other.Id)
            return -1;

        return 0;
    }
}

class Program {
    static void Main() {
        Tree<Employee> empTree = new Tree<Employee>(new Employee { Id = 1, FirstName = "Janet", LastName = "Gates", Department = "IT" });
        empTree.Insert(new Employee { Id = 2, FirstName = "O", LastName = "G", Department = "Marketing" });
        empTree.Insert(new Employee { Id = 4, FirstName = "K", LastName = "H", Department = "IT" });
        empTree.Insert(new Employee { Id = 6, FirstName = "L", LastName = "H", Department = "Sales" });
        empTree.Insert(new Employee { Id = 3, FirstName = "E", LastName = "L", Department = "Sales" });
        empTree.Insert(new Employee { Id = 5, FirstName = "D", LastName = "L", Department = "Marketing" });

        var allEmployees = from e in empTree.ToList<Employee>()
                           select e;

        foreach (var emp in allEmployees)
            Console.WriteLine(emp);

    }
}

    

   
 

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

class LinqDemo {
    static void Main() {
        string[] names = { "J", "P", "G", "P" };

        IEnumerable<string> query = names
          .Where(n => n.Contains("a"))
          .OrderBy(n => n.Length)
          .Select(n => n.ToUpper());

        foreach (string name in query) Console.Write(name + "|");
    }
}

    

   
 

using System;
using System.Collections.Generic;
using System.Linq;
public class MainClass {
    public static void Main() {
        string[] names = { "Tom", "Dick", "Harry", "Mary", "Jay" };
        IEnumerable<string> filtered = names.Where(n => n.Contains("a"));
        IEnumerable<string> sorted = filtered.OrderBy(n => n.Length);
        IEnumerable<string> finalQuery = sorted.Select(n => n.ToUpper());

        foreach (string name in filtered)
            Console.Write(name + "|");        

        Console.WriteLine();
        foreach (string name in sorted)
            Console.Write(name + "|");        

        Console.WriteLine();
        foreach (string name in finalQuery)
            Console.Write(name + "|");        
    }
}

    

   
 

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"A", "B", "Bu", "Bush", "C", "Cl"};

        var nameObjs = presidents.Select((p, i) => new { Index = i, LastName = p });

        foreach (var item in nameObjs)
            Console.WriteLine("{0}. {1}", item.Index + 1, item.LastName);

    }
}

    

   
 

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"A", "Ar", "Buc", "Bush", "Carte", "Clevel"};
        var nameObjs = presidents.Select(p => new { LastName = p, Length = p.Length });
        foreach (var item in nameObjs)
            Console.WriteLine("{0} is {1} characters long.", item.LastName, item.Length);

    }
}

    

   
 


using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"A", "Ar", "Buc", "Bush", "Carte", "Clevel"};

        var nameObjs = presidents.Select(p => new { p, p.Length });

        foreach (var item in nameObjs)
            Console.WriteLine(item);
    }
}

    

   
 

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"Ad", "Ar", "Bu", "Bu", "Ca", "Cl"};

        IEnumerable<string> sequence = presidents.Where((p, i) => (i &amp; 1) == 1);

        foreach (string s in sequence)
            Console.WriteLine("{0}", s);

    }
}