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RandomizedSet.kt
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package questions
import _utils.UseCommentAsDocumentation
import questions.common.ClassInvoker
import utils.shouldBe
import utils.shouldBeOneOf
/**
*Implement the RandomizedSet class:
* * `RandomizedSet()` Initializes the RandomizedSet object.
* * `bool insert(int val)` Inserts an item val into the set if not present. Returns true if not present, false otherwise.
* * `bool remove(int val)` Removes an item val from the set if present. Returns true if the item was present, false otherwise.
* * `int getRandom()` Returns a random element from the current set of elements.
* [Source](https://leetcode.com/problems/insert-delete-getrandom-o1/)
*/
@UseCommentAsDocumentation
class RandomizedSet {
private var array = Array<Int?>(5) { null }
private val charToIndex = mutableMapOf<Int, Int>()
private var lastInsertedAt = -1
private val rand = java.util.Random()
fun insert(`val`: Int): Boolean {
if (charToIndex.containsKey(`val`)) {
return false
}
lastInsertedAt++
if (lastInsertedAt > array.lastIndex) {
val newArr = Array<Int?>(lastInsertedAt * 2) { null }
System.arraycopy(array, 0, newArr, 0, array.size)
array = newArr
}
array[lastInsertedAt] = `val`
charToIndex[`val`] = lastInsertedAt
return true
}
fun remove(`val`: Int): Boolean {
val index = charToIndex[`val`] ?: return false
// GOTCHA: Swap last element with [index]
array[index] = array[lastInsertedAt]
// Update the map
charToIndex[array[lastInsertedAt]!!] = index
// Delete
array[lastInsertedAt] = null
lastInsertedAt--
charToIndex.remove(`val`)
return true
}
fun getRandom(): Int {
return array[rand.nextInt(lastInsertedAt + 1)]!!
}
}
fun main() {
run {
val invoker = ClassInvoker<IntArray, Int>(
listOf(
"RandomizedSet",
"insert",
"getRandom",
"getRandom",
"getRandom",
"insert",
"insert",
"insert",
"insert",
"insert",
"getRandom",
"getRandom",
"insert",
"getRandom",
"insert",
"insert",
"getRandom",
"getRandom",
"getRandom",
"getRandom",
"remove",
"insert",
"getRandom",
"getRandom",
"insert",
"remove",
"remove",
"insert",
"getRandom",
"getRandom",
"insert",
"insert",
"getRandom",
"remove",
"remove",
"insert",
"remove",
"getRandom",
"getRandom",
"remove",
"getRandom",
"insert",
"insert",
"getRandom",
"remove",
"remove",
"remove",
"getRandom",
"insert",
"insert",
"insert",
"insert",
"getRandom",
"insert",
"getRandom",
"remove",
"insert",
"insert",
"insert",
"getRandom",
"getRandom",
"insert",
"getRandom",
"insert",
"insert",
"getRandom",
"getRandom",
"remove",
"getRandom",
"remove",
"insert",
"getRandom",
"insert",
"insert",
"insert",
"getRandom",
"insert",
"insert",
"getRandom",
"insert",
"getRandom",
"insert",
"getRandom",
"getRandom",
"getRandom",
"insert",
"getRandom",
"getRandom",
"insert",
"insert",
"insert",
"getRandom",
"remove",
"insert",
"insert",
"getRandom",
"insert",
"insert",
"insert",
"insert"
)
) {
it.getOrNull(0)
}
invoker.invoke(
listOf(
intArrayOf(),
intArrayOf(-7),
intArrayOf(),
intArrayOf(),
intArrayOf(),
intArrayOf(6),
intArrayOf(7),
intArrayOf(10),
intArrayOf(3),
intArrayOf(8),
intArrayOf(),
intArrayOf(),
intArrayOf(-8),
intArrayOf(),
intArrayOf(6),
intArrayOf(-8),
intArrayOf(),
intArrayOf(),
intArrayOf(),
intArrayOf(),
intArrayOf(2),
intArrayOf(2),
intArrayOf(),
intArrayOf(),
intArrayOf(5),
intArrayOf(-5),
intArrayOf(-8),
intArrayOf(-8),
intArrayOf(),
intArrayOf(),
intArrayOf(-4),
intArrayOf(10),
intArrayOf(),
intArrayOf(7),
intArrayOf(-1),
intArrayOf(8),
intArrayOf(-6),
intArrayOf(),
intArrayOf(),
intArrayOf(9),
intArrayOf(),
intArrayOf(7),
intArrayOf(0),
intArrayOf(),
intArrayOf(-10),
intArrayOf(-4),
intArrayOf(-3),
intArrayOf(),
intArrayOf(-4),
intArrayOf(-5),
intArrayOf(8),
intArrayOf(-2),
intArrayOf(),
intArrayOf(-9),
intArrayOf(),
intArrayOf(7),
intArrayOf(-2),
intArrayOf(7),
intArrayOf(4),
intArrayOf(),
intArrayOf(),
intArrayOf(-6),
intArrayOf(),
intArrayOf(-8),
intArrayOf(2),
intArrayOf(),
intArrayOf(),
intArrayOf(9),
intArrayOf(),
intArrayOf(-1),
intArrayOf(3),
intArrayOf(),
intArrayOf(0),
intArrayOf(-3),
intArrayOf(-1),
intArrayOf(),
intArrayOf(-8),
intArrayOf(-10),
intArrayOf(),
intArrayOf(3),
intArrayOf(),
intArrayOf(4),
intArrayOf(),
intArrayOf(),
intArrayOf(),
intArrayOf(-10),
intArrayOf(),
intArrayOf(),
intArrayOf(0),
intArrayOf(-2),
intArrayOf(5),
intArrayOf(),
intArrayOf(-2),
intArrayOf(5),
intArrayOf(10),
intArrayOf(),
intArrayOf(9),
intArrayOf(0),
intArrayOf(7),
intArrayOf(-2)
),
)
}
run {
val set = RandomizedSet()
set.apply {
insert(0) shouldBe true
getRandom() shouldBe 0
remove(0) shouldBe true
insert(0) shouldBe true
}
}
run {
val randomizedSet = RandomizedSet()
randomizedSet.insert(1) shouldBe true // Inserts 1 to the set. Returns true as 1 was inserted successfully.
randomizedSet.remove(2) shouldBe false // Returns false as 2 does not exist in the set.
randomizedSet.insert(2) shouldBe true // Inserts 2 to the set, returns true. Set now contains [1,2].
randomizedSet.getRandom() shouldBeOneOf listOf(1, 2) // getRandom() should return either 1 or 2 randomly.
randomizedSet.remove(1) shouldBe true // Removes 1 from the set, returns true. Set now contains [2].
randomizedSet.insert(2) shouldBe false // 2 was already in the set, so return false.
randomizedSet.getRandom() shouldBe 2 // Since 2 is the only number in the set, getRandom() will always return 2.
randomizedSet.remove(2) shouldBe true
randomizedSet.insert(4) shouldBe true
randomizedSet.insert(5) shouldBe true
randomizedSet.insert(6) shouldBe true
for (i in 0..100) {
randomizedSet.getRandom() shouldBeOneOf listOf(4, 5, 6)
}
}
}