Remove duplicate lists from a parent list using hashset in c# -

i have parent list contains several child lists. , these inner lists contain column objects.

list<list<column>> listofallcolumns;  public class column {     public string sectionname;     public string stirruptype;     public int stirrupsize;     public double stirrupspacing; } 

let's child lists contain different column objects this:

list1 = {c1, c1, c2} list2 = {c1, c2, c1} list3 = {c2, c3} list4 = {c1,c1, c2} 

and parent list contains these lists:

listofallcolumns = {list1, list2, list3, list4} 

now want method removes duplicate lists listofallcolumns list. example, list above , remove list4.

list1: c1,c1,c2 list2: c1,c2,c1 list3: c2,c3 list4: c1,c1,c2 (it equal list1 duplicate) 

i know can done using linq , distinct method want using hashset.

• by way order important, example {c1, c2, c1} different {c2,c1,c1}.

update 1:

here tricky part. order important inside child lists not important in parent list. list1:{c1, c2} , list2: {c2,c1} different not important how added parent list, listofallcolumns:{list1, list2} , listofallcolumns:{list2,lis1} same thing.

here code have tried:

column c1 = new column() { sectionname = "c50", stirruptype = "tie" }; column c2 = new column() { sectionname = "c50", stirruptype = "spiral" }; column c3 = new column() { sectionname = "c40", stirruptype = "tie" };   list<column> list1 = new list<column>() { c1, c1, c2 }; list<column> list2 = new list<column>() { c1, c2, c1 }; list<column> list3 = new list<column>() { c2, c3 }; list<column> list4 = new list<column>() { c1, c1, c2 };   list<list<column>> listofallcolumns = new list<list<column>>() { list1, list2, list3, list4 };   hashset<list<column>> hs = new hashset<list<column>>(); list<list<column>> uniquelistofallcolumns = new list<list<column>>();  foreach (var c in listofallcolumns) {     if (hs.add(c))     {         // logic hashset should recognize duplicates in part.         uniquelistofallcolumns.add(c);     } } 

a similar question here: c#: remove duplicate values dictionary?

you should override hashset methods contains , equals (where can implement ordered checking).

then insert implementation of hashset parentlist. check if hashsetcontains list<column> , insert if not there.

but linq seems best solution.