Birthday problem: Difference between revisions
Add Scala implementation
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4 independant people in a group of 187 share a common birthday. ( 50.3)
5 independant people in a group of 313 share a common birthday. ( 50.3)</pre>
=={{header|Scala}}==
{{trans|Java}}
<syntaxhighlight lang="Scala">
import scala.util.Random
import scala.util.control.Breaks._
object Test {
def equalBirthdays(
nSharers: Int,
groupSize: Int,
nRepetitions: Int
): Double = {
val rand = new Random(1)
var eq = 0
for (_ <- 1 to nRepetitions) {
val group = new Array[Int](365)
for (_ <- 1 to groupSize) {
val birthday = rand.nextInt(group.length)
group(birthday) += 1
}
if (group.exists(_ >= nSharers)) eq += 1
}
(eq * 100.0) / nRepetitions
}
def main(args: Array[String]): Unit = {
var groupEst = 2
for (sharers <- 2 until 6) {
// Coarse.
var groupSize = groupEst + 1
while (equalBirthdays(sharers, groupSize, 100) < 50.0)
groupSize += 1
// Finer.
val inf = (groupSize - (groupSize - groupEst) / 4.0).toInt
breakable({
for (gs <- inf until groupSize + 999) {
val eq = equalBirthdays(sharers, groupSize, 250)
if (eq > 50.0) {
groupSize = gs
break
}
}
})
// Finest.
breakable({
for (gs <- (groupSize - 1) until groupSize + 999) {
val eq = equalBirthdays(sharers, gs, 50000)
if (eq > 50.0) {
groupEst = gs
println(
f"$sharers independent people in a group of $gs share a common birthday. ($eq%5.1f)"
)
break
}
}
})
}
}
}
</syntaxhighlight>
{{out}}
<pre>
2 independent people in a group of 23 share a common birthday. ( 50.6)
3 independent people in a group of 87 share a common birthday. ( 50.4)
4 independent people in a group of 187 share a common birthday. ( 50.1)
5 independent people in a group of 314 share a common birthday. ( 50.2)
</pre>
=={{header|SQL}}==
birthday.sql
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