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troubleshooting Question

How can C# match substrings very fast?

Avatar of chaffinsjc
chaffinsjc asked on
C#
3 Comments1 Solution535 ViewsLast Modified:
In the problem example below, each item in "usableItems" is looked for in the "originalItems" data structure. Each item that is not found is placed in the discardedItems string array.

PROBLEM EXAMPLE
string[] usableItems = {"1", "b7", "13" };
string[] originalItems = {"1", "3", "5", "b7", "9", "11", "13" };
string[] discardedItems = { "3", "5", "9", "11" }; //final result

How should a C# program structure the data and logic to minimize the time to build the final string array named "discardedItems"?

I think Regex and IndexOf would probably be slow. And I'm not sure about using char[] arrays somehow. Also, there might be consideration of a dictionary for quick lookup, but then establishing the dictionary will also require time. Hmmm.

SOME RULES (just want to explain clearly):
(1) The items numerically represent the notes in common piano chords. There are hundreds of chords, with variations in sharps, flats, and number of items to match and/or be matched. Typical items are "3", "#5", "7", "b7", "#9", "b11", "11", "#11", "b13", etc.
(2) The items always increase numerically from left to right.
(3) Items do not repeat.
(4) There can be from 1 to 7 "originalItems".
(5) There can be from 1 to 7 "usableItems".
(6) There will never be more "usableItems" than "originalItems".
(7) Each item in "usableItems" ALWAYS DOES EXIST in "originalItems".

NOTE: To present this problem, string arrays are used for "usableItems" and "originalItems", but only the final result "discardedItems" must be a string array.

I would sincerely appreciate some code ideas.
ASKER CERTIFIED SOLUTION
Avatar of Fernando Soto
Commented:
This problem has been solved!
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