Code archives/Algorithms/Linked Type Lists (Updated)
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| This method allows a program quickly to search a large number of similar types by creating a linked list through which they can be indexed together. This is MUCH faster than the "needle in a haystack" method of searching large numbers of types with a For/Each loop. Clever programmers can use this algorithm to link types together in all sorts of funky ways. UPDATE: Expanded method allows bidirectional searches and an easier way to insert and delete types in the middle of a list. |
Type ship Field x Field y Field pv.ship ; This will point to the previous ship in the linked list Field nx.ship ; And this points to the next one End Type Type destroyer Field lastship.ship ; Points to the last ship in the string ... Field firstship.ship ; ... and the first one. End Type Type fighter Field lastship.ship Field firstship.ship End Type Global destroyer.destroyer = New destroyer Global fighter.fighter = New fighter ; Let's make some destroyers For x = 1 To 100 d.ship = New ship d\pv = destroyer\lastship If destroyer\lastship <> Null Then destroyer\lastship\nx = d Else destroyer\firstship = d destroyer\lastship = d Next ; Now we need fighters For x = 1 To 250 f.ship = New ship f\pv = fighter\lastship If fighter\lastship <> Null Then fighter\lastship\nx = f Else fighter\firstship = f fighter\lastship = f Next ; Move all the fighters one pixel to the left, in reverse order scratch.ship = fighter\lastship Repeat scratch\x = scratch\x - 1 scratch = scratch\pv Until scratch = Null ; Draw all the destroyers, in forward order scratch.ship = destroyer\firstship Repeat DrawImage destroyerimage,scratch\x,scratch\y scratch = scratch\nx Until scratch = Null ; Insert a fighter after the first one in the list f.ship = New ship f\nx = fighter\firstship\nx f\pv = fighter\firstship fighter\firstship\nx = f ; Add a new destroyer to the end of the list d.ship = New ship d\pv = destroyer\lastship destroyer\lastship\nx = d destroyer\lastship = d ; Delete the 15th destroyer scratch.ship = destroyer\firstship For x = 1 To 14 scratch = scratch\nx Next scratch\nx\pv = scratch\pv scratch\pv\nx = scratch\nx Delete scratch ; Move all ships three pixels down For scratch.ship = Each ship scratch\y = scratch\y + 3 Next |