@Test
public void shouldConvertToList() {
final Value<Integer> value = of(1, 2, 3);
final List<Integer> list = value.toList();
if (value.isSingleValued()) {
assertThat(list).isEqualTo(List.of(1));
} else {
assertThat(list).isEqualTo(List.of(1, 2, 3));
}
}
/**
* <strong>Problem 37 Truncatable primes</strong>
*
* <p>The number 3797 has an interesting property. Being prime itself, it is possible to
* continuously remove digits from left to right, and remain prime at each stage: 3797, 797, 97,
* and 7. Similarly we can work from right to left: 3797, 379, 37, and 3.
*
* <p>Find the sum of the only eleven primes that are both truncatable from left to right and
* right to left.
*
* <p>NOTE: 2, 3, 5, and 7 are not considered to be truncatable primes.
*
* <p>See also <a href="https://projecteuler.net/problem=37">projecteuler.net problem 37</a>.
*/
@Test
public void shouldSolveProblem37() {
assertThat(isTruncatablePrime(3797)).isTrue();
List.of(2, 3, 5, 7).forEach(i -> assertThat(isTruncatablePrime(7)).isFalse());
assertThat(sumOfTheElevenTruncatablePrimes()).isEqualTo(748_317);
}
/**
* <strong>Problem 39 Integer right triangles</strong>
*
* <p>If <i>p</i> is the perimeter of a right angle triangle with integral length sides,
* {<i>a,b,c</i>}, there are exactly three solutions for <i>p</i> = 120.
*
* <p>{20,48,52}, {24,45,51}, {30,40,50}
*
* <p>For which value of <i>p</i> ≤ 1000, is the number of solutions maximised?
*
* <p>See also <a href="https://projecteuler.net/problem=39">projecteuler.net problem 39</a>.
*/
@Test
public void shouldSolveProblem39() {
assertThat(SOLUTIONS_FOR_PERIMETERS_UP_TO_1000.get(120))
.isEqualTo(some(List.of(Tuple.of(20, 48, 52), Tuple.of(24, 45, 51), Tuple.of(30, 40, 50))));
assertThat(perimeterUpTo1000WithMaximisedNumberOfSolutions()).isEqualTo(840);
}
private static boolean isTruncatablePrime(int prime) {
return Match(prime)
.of(
Case(
$(p -> p > 7),
p -> {
final CharSeq primeSeq = CharSeq.of(Integer.toString(p));
return List.rangeClosed(1, primeSeq.length() - 1)
.flatMap(i -> List.of(primeSeq.drop(i), primeSeq.dropRight(i)))
.map(CharSeq::mkString)
.map(Long::valueOf)
.forAll(Utils.MEMOIZED_IS_PRIME::apply);
}),
Case($(), false));
}
@Test
public void shouldConvertToSeq() {
final Seq<?> actual = createIntTuple(1, 0, 0, 0, 0, 0, 0, 0).toSeq();
assertThat(actual).isEqualTo(List.of(1, 0, 0, 0, 0, 0, 0, 0));
}