So I have to arraylists which represent integers for example num1 = <-1,4,5>
would represent -145 and num2= <2,3,6>
would represent 236.
ArrayList<Integer> num1 = new ArrayList<>(Arrays.asList(1,2,9));
ArrayList<Integer> num2 = new ArrayList<>(Arrays.asList(-5,5));
final int sign = num1.get(0) < 0 ^ num2.get(0) < 0 ? -1 : 1;
So sign is supposed to determine the sign that would occur from multiplying num1 with num2 ( -145*236
would be a negative number). So comparison operators are non associative so this should be an equivalent expression:
sign = (num1.get(0) < 0 ^ num2.get(0)) && (0 ^ num2.get(0) < 0) ? -1:1;
Whats confusing me is why is num2.get(0)
being XOR'ed with 0 because that does not alter num2.get(0)
at all.
Also lets say num2.get(0) = -2
and num1.get(0) = -3
then if we evaluated for sign we'd get sign=-1. Because (-3< 0 ^ -2) AND (0 ^ -2 < 0)? -1:1;
(-3< 0 ^ -2) AND (0 ^ -2 < 0)? -1:1;
evaluates to -1.
But this would be wrong -3*-2 should be a positive number. So what am I missing because I know this code is correct (it's from a textbook).
num1.get(0) < 0 ^ num2.get(0) < 0 ? -1 : 1
is evaluated as
((num1.get(0) < 0) ^ (num2.get(0) < 0)) ? -1 : 1
This is determined by operator precedence. Comparison operators being non-associative has nothing to do with it whatsoever.
Whats confusing me is why is num2.get(0) being XOR'ed with 0
It isn't.
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