Find the missing permutation: Difference between revisions
Added Kotlin
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,/p2@&~(p2:{x@m@&n=(#?:)'m:!n#n:#x}[*p]) _lin p
</lang>
=={{header|Kotlin}}==
<lang scala>// version 1.1.1
fun <T> permute(input: List<T>): List<List<T>> {
if (input.size == 1) return listOf(input)
val perms = mutableListOf<List<T>>()
val toInsert = input[0]
for (perm in permute(input.drop(1))) {
for (i in 0..perm.size) {
val newPerm = perm.toMutableList()
newPerm.add(i, toInsert)
perms.add(newPerm)
}
}
return perms
}
fun <T> missingPerms(input: List<T>, perms: List<List<T>>) = permute(input) - perms
fun main(args: Array<String>) {
val input = listOf('A', 'B', 'C', 'D')
val strings = listOf(
"ABCD", "CABD", "ACDB", "DACB", "BCDA", "ACBD", "ADCB", "CDAB",
"DABC", "BCAD", "CADB", "CDBA", "CBAD", "ABDC", "ADBC", "BDCA",
"DCBA", "BACD", "BADC", "BDAC", "CBDA", "DBCA", "DCAB"
)
val perms = strings.map { it.toList() }
val missing = missingPerms(input, perms)
if (missing.size == 1)
print("The missing permutation is ${missing[0].joinToString("")}")
else {
println("There are ${missing.size} missing permutations, namely:\n")
for (perm in missing) println(perm.joinToString(""))
}
}</lang>
{{out}}
<pre>
The missing permutation is DBAC
</pre>
=={{header|Lua}}==
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