Kotlin check if two lists are the same apart from one list having an additional element?

Question

So I have list A and list B.
A is of size n and B is of size n + 1.
I need to know if all elements in A are the same as all elements in B.sublist(0, n - 1).

A: [5,7,2,9]  
B: [5,7,2,9,1]
true

A: [5,7,2,9]  
B: [5,7,2,9,9]
true

A: [7,5,2,9]  
B: [5,7,2,9,1]
false (order matters)

Is there any elegant ways to do this using library functions maybe?

score 1 · Answer 1 · answered Apr 16 '20 at 14:59

1

List has a subList method, so you can express your conditions directly:

(b.size() == a.size() + 1) && (b.subList(0, a.size()).equals(a))

answered Apr 16 '20 at 14:59

chrylis -cautiouslyoptimistic-

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jbarat · Answer 2 · 2020-04-16T15:00:52.587

0

Very simple solution:

return B.take(A.size+1) == A

edited Apr 16 '20 at 15:00

answered Apr 16 '20 at 14:56

jbarat

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Does this limit to 1 extra element? – chrylis -cautiouslyoptimistic- Apr 16 '20 at 14:57
@chrylis-onstrike- you are correct it doesn't, I correct it. – jbarat Apr 16 '20 at 15:00

score 0 · Answer 3 · answered Apr 16 '20 at 14:59

0

As long as b cannot be empty, you could write:

return a == b.dropLast(1)

answered Apr 16 '20 at 14:59

Ben P.

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Kotlin check if two lists are the same apart from one list having an additional element?

3 Answers3