Brain teaser

Friend of mine ask me a question: how to switch values of two variables (Integer type to be strict) but without using another one?

Use this spock spec as problem definition:

@Unroll

def "should switch variables (#a,#b) without additional variable"() {

expect:

new Switcher(a, b).switchVariables().toString() == result

where:

a | b | result

1 | 2 | "a=2 b=1"

10 | 20 | "a=20 b=10"

-10 | -20 | "a=-20 b=-10"

20 | 10 | "a=10 b=20"

-20 | -10 | "a=-10 b=-20"

0 | 10 | "a=10 b=0"

10 | 0 | "a=0 b=10"

-10 | 0 | "a=0 b=-10"

0 | 0 | "a=0 b=0"

0 | -1 | "a=-1 b=0"

10 | 10 | "a=10 b=10"

Integer.MAX_VALUE | Integer.MAX_VALUE | "a=" + Integer.MAX_VALUE + " b=" + Integer.MAX_VALUE

Integer.MIN_VALUE | Integer.MAX_VALUE | "a=" + Integer.MAX_VALUE + " b=" + Integer.MIN_VALUE

Integer.MIN_VALUE | Integer.MIN_VALUE | "a=" + Integer.MIN_VALUE + " b=" + Integer.MIN_VALUE

1 | Integer.MAX_VALUE | "a=" + Integer.MAX_VALUE + " b=1"

Integer.MIN_VALUE | 1 | "a=1 b=" + Integer.MIN_VALUE

-1 | Integer.MIN_VALUE | "a=" + Integer.MIN_VALUE + " b=-1"

}

You can find working solution on https://github.com/piotrpietrzak/gatchaman/tree/swicher

Have fun!