August 26, 2024
P11 - Modified run-length encoding.
Modify the result of problem P10 in such a way that if an element has no duplicates it is simply copied into the result list. Only elements with duplicates are transferred as (N, E) terms. Example:
> encodeModified("aaaabccaadeeee".toList())
[(4, a), b, (2, c), (2, a), d, (4, e)]kotlin
package org.kotlin99.lists
import com.natpryce.hamkrest.assertion.assertThat
import com.natpryce.hamkrest.equalTo
import org.junit.Test
@Suppress("IMPLICIT_CAST_TO_ANY")
// Note that T has upper bound of Any (not nullable value)
fun <T: Any> encodeModifies(list: List<T>): List<Any> =
pack(list).map {
if (it.size == 1) it.first()
else Pair(it.size, it.first())
}
class P11Test {
@Test fun `modified run-length encoding`() {
assertThat(encodeModifies("aaaabccaadeeee".toList()), equalTo(listOf<Any>(
Pair(4, 'a'), 'b', Pair(2, 'c'), Pair(2, 'a'), 'd', Pair(4, 'e')
)))
}
}
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