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javaarraysmultidimensional-arrayduplicatesrepeat
Connor
Connor

Reputation: 698

Java 2D Array - Detect Duplicate Values

What is the easiest/simplest/most efficient way to detect if a 2D array has duplicate/repeating values?

e.g. 2D Array:

{{2, 17, 4, 5} {3, 2, 34 9}}

This matrix has multiple "2" values.

I want to set a boolean to true if this is the case.

Thanks in advance!

Upvotes: 1

Views: 1127

Answers (1)

Daniel Kaplan
Daniel Kaplan

Reputation: 67370

I think the best you can do here is O(n) because you won't know if the very last element is a duplicate until you check it. Here's an idea:

Have a Set of values. Iterate the 2d array and for each element do this:

if (!set.add(element))
   // a duplicate was found!

This works because Set.add returns "true if this set did not already contain the specified element"

Upvotes: 3

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