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24 game/Solve: Difference between revisions
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Line 236:
<lang r>solve24(c(6, 7, 9, 5)) # A solution is: 6 + ( 7 - 5 ) * 9
solve24(c(9, 9, 9, 9)) # No solution could be found</lang>
=={{header|Ruby}}==
Line 379 ⟶ 321:
8 * (9 - (3 * 2))
8 / (2 / (9 - 3))</pre>
=={{header|Scala}}==
A non-interactive player.
<lang scala>def permute(l: List[Double]): List[List[Double]] = l match {
case Nil => List(Nil)
case x :: xs =>
for {
ys <- permute(xs)
position <- 0 to ys.length
(left, right) = ys splitAt position
} yield left ::: (x :: right)
}
def computeAllOperations(l: List[Double]): List[(Double,String)] = l match {
case Nil => Nil
case x :: Nil => List((x, "%1.0f" format x))
case x :: xs =>
for {
(y, ops) <- computeAllOperations(xs)
(z, op) <-
if (y == 0)
List((x*y, "*"), (x+y, "+"), (x-y, "(-"))
else
List((x*y, "*"), (x/y, "/"), (x+y, "+"), (x-y, "-"))
} yield (z, "(%1.0f%s%s)" format (x,op,ops))
}
def hasSolution(l: List[Double]) = permute(l) flatMap computeAllOperations filter (_._1 == 24) map (_._2)</lang>
Example:
<pre>
val problemsIterator = (
Iterator
continually List.fill(4)(scala.util.Random.nextInt(9) + 1 toDouble)
filter (!hasSolution(_).isEmpty)
)
val solutionIterator = problemsIterator map hasSolution
scala> solutionIterator.next
res8: List[String] = List((3*(5-(3-6))), (3*(5-(3-6))), (3*(5+(6-3))), (3+(6+(3*5))), (3*(6-(3-5))), (3+(6+(5*3))), (3*(
6+(5-3))), (3*(5+(6-3))), (3+(6+(5*3))), (3*(6+(5-3))), (6+(3+(5*3))), (6*(5-(3/3))), (6*(5-(3/3))), (3+(6+(3*5))), (3*(
6-(3-5))), (6+(3+(3*5))), (6+(3+(3*5))), (6+(3+(5*3))))
scala> solutionIterator.next
res9: List[String] = List((4-(5*(5-9))), (4-(5*(5-9))), (4+(5*(9-5))), (4+(5*(9-5))), (9-(5-(4*5))), (9-(5-(5*4))), (9-(
5-(4*5))), (9-(5-(5*4))))
scala> solutionIterator.next
res10: List[String] = List((2*(4+(3+5))), (2*(3+(4+5))), (2*(3+(5+4))), (4*(3-(2-5))), (4*(3+(5-2))), (2*(4+(5+3))), (2*
(5+(4+3))), (2*(5+(3+4))), (4*(5-(2-3))), (4*(5+(3-2))))
scala> solutionIterator.next
res11: List[String] = List((4*(5-(2-3))), (2*(4+(5+3))), (2*(5+(4+3))), (2*(5+(3+4))), (2*(4+(3+5))), (2*(3+(4+5))), (2*
(3+(5+4))), (4*(5+(3-2))), (4*(3+(5-2))), (4*(3-(2-5))))
</pre>
=={{header|Tcl}}==
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