Move-to-front algorithm: Difference between revisions
Added Kotlin
(→{{header|Haskell}}: 2nd thoughts re test: used point free form plus pointed expansion in comment) |
(Added Kotlin) |
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Line 1,053:
bananaaa => [1,1,13,1,1,1,0,0] => bananaaa
hiphophiphop => [7,8,15,2,15,2,2,3,2,2,3,2] => hiphophiphop</lang>
=={{header|Kotlin}}==
<lang scala>// version 1.1.2
fun encode(s: String): IntArray {
if (s.isEmpty()) return intArrayOf()
val symbols = "abcdefghijklmnopqrstuvwxyz".toCharArray()
val result = IntArray(s.length)
for ((i, c) in s.withIndex()) {
val index = symbols.indexOf(c)
if (index == -1)
throw IllegalArgumentException("$s contains a non-alphabetic character")
result[i] = index
if (index == 0) continue
for (j in index - 1 downTo 0) symbols[j + 1] = symbols[j]
symbols[0] = c
}
return result
}
fun decode(a: IntArray): String {
if (a.isEmpty()) return ""
val symbols = "abcdefghijklmnopqrstuvwxyz".toCharArray()
val result = CharArray(a.size)
for ((i, n) in a.withIndex()) {
if (n !in 0..25)
throw IllegalArgumentException("${a.contentToString()} contains an invalid number")
result[i] = symbols[n]
if (n == 0) continue
for (j in n - 1 downTo 0) symbols[j + 1] = symbols[j]
symbols[0] = result[i]
}
return result.joinToString("")
}
fun main(args: Array<String>) {
val strings = arrayOf("broood", "bananaaa", "hiphophiphop")
val encoded = Array<IntArray?>(strings.size) { null }
for ((i, s) in strings.withIndex()) {
encoded[i] = encode(s)
println("${s.padEnd(12)} -> ${encoded[i]!!.contentToString()}")
}
println()
val decoded = Array<String?>(encoded.size) { null }
for ((i, a) in encoded.withIndex()) {
decoded[i] = decode(a!!)
print("${a.contentToString().padEnd(38)} -> ${decoded[i]!!.padEnd(12)}")
println(" -> ${if (decoded[i] == strings[i]) "correct" else "incorrect"}")
}
}</lang>
{{out}}
<pre>
broood -> [1, 17, 15, 0, 0, 5]
bananaaa -> [1, 1, 13, 1, 1, 1, 0, 0]
hiphophiphop -> [7, 8, 15, 2, 15, 2, 2, 3, 2, 2, 3, 2]
[1, 17, 15, 0, 0, 5] -> broood -> correct
[1, 1, 13, 1, 1, 1, 0, 0] -> bananaaa -> correct
[7, 8, 15, 2, 15, 2, 2, 3, 2, 2, 3, 2] -> hiphophiphop -> correct
</pre>
=={{header|Lua}}==
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