[Week4] 전현수: 근손실, 톱니바퀴, 트리의 부모 찾기, 회의실 배정, 지름길 #18
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| fun <T> Array<T>.second(): T = this[1] | ||
| fun <T> Array<T>.third(): T = this[2] | ||
| fun <T> Array<T>.fourth(): T = this[3] |
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@gongdongho12
보기 좋으라고 해봤는데...ㅎㅎ 안쓰느니만 못하나요??
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이거 왜 안지우는거에요? Iterator는 그냥 자동으로 destructure 지원되서 사용 안해도 되요!
Closed
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| val gear1 = gearList.first() | ||
| val gear2 = gearList.second() | ||
| val gear3 = gearList.third() | ||
| val gear4 = gearList.fourth() |
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@soopeach 이건 어떠세요?
val (gear1, gear2, gear3, gear4) = gearList
soopeach
changed the title
| * | ||
| */ | ||
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| val exerciseKitList = mutableListOf<Int>() |
| possibleCaseCnt++ | ||
| return | ||
| } | ||
| for (index in 0 until exerciseKitList.size) { |
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이부분 exerciseKitList.forEachIndexed 했으면 어땠을까요?
gongdongho12
reviewed
Nov 3, 2022
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| val shortCutGraph = Array(10001) { | ||
| mutableListOf<ShortCutData>() | ||
| } | ||
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| repeat(shortCutCnt) { | ||
| val (start, end, shortCutDistance) = readln().split(" ").map { it.toInt() } | ||
| // 도착지점이 고속도로의 길이를 넘거나 지름길이 도로보다 길지 않은 경우에만 지름길 생성 | ||
| if ((end > highWayLength).not() && | ||
| (end - start <= shortCutDistance).not() | ||
| ) shortCutGraph[end].add(ShortCutData(start, shortCutDistance)) | ||
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| } |
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이부분 코틀린의 groupBy를 활용해보면 쓸데없는 데이터는 안 만들 수 있지 않을까요?
val shortCutGraph: Map<Int, List<ShortCutData>> = (0 until shortCutCnt).mapNotNull {
val (start, end, shortCutDistance) = readln().split(" ").map { it.toInt() }
if (end <= highWayLength && (end - start) > shortCutDistance) {
end to ShortCutData(start, shortCutDistance)
} else null
}.groupBy({ it.first }, { it.second })
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| for (end in 1..highWayLength) { | ||
| dp[end] = dp[end - 1] + 1 | ||
| if (shortCutGraph[end].isNotEmpty()) { | ||
| shortCutGraph[end].forEach { shortCutData -> | ||
| dp[end] = min(dp[end], dp[shortCutData.start] + shortCutData.distance) | ||
| } | ||
| } | ||
| } |
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이부분도 minOf를 써서 잘 활용해서
(1..highWayLength).forEach { end ->
dp[end] = dp[end - 1] + 1
dp[end] = shortCutGraph[end]?.minOf {
dp[it.start] + it.distance
}?.takeIf { it < dp[end] } ?: dp[end]
}minOf 한 값이 dp[end] 보다 작으면 진짜 최솟값인거고 아니면 null 리턴해서 dp[end]를 리턴하는거에요!
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| class Gear(stateData: String) { | ||
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| private val state = IntArray(8) | ||
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| init { | ||
| stateData.forEachIndexed { index, charNum -> | ||
| state[index] = charNum.digitToInt() | ||
| } | ||
| } |
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class Gear(val state: IntArray) {
constructor(str: String): this(str.map { it.digitToInt() }.toIntArray())
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| val gearList = Array(4) { | ||
| Gear(readln()) | ||
| } | ||
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| val affectedInfo = Array(4) { | ||
| mutableListOf<Int>() | ||
| } | ||
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| fun solution() { | ||
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| val gear1 = gearList.first() | ||
| val gear2 = gearList.second() | ||
| val gear3 = gearList.third() | ||
| val gear4 = gearList.fourth() | ||
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| val rotateCnt = readln().toInt() | ||
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| val rotateInfoList = Array(rotateCnt) { | ||
| val (gearNum, dir) = readln().split(" ").map { it.toInt() } | ||
| RotateInfo(gearNum, dir) | ||
| } | ||
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| rotateInfoList.forEach { rotateInfo -> | ||
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| val (gearNum, dir) = rotateInfo | ||
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| val (firstLeft, firstRight) = gear1.getPole() | ||
| val (secondLeft, secondRight) = gear2.getPole() | ||
| val (thirdLeft, thirdRight) = gear3.getPole() | ||
| val (fourthLeft, fourthRight) = gear4.getPole() | ||
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| // 회전에 영향을 받을 기어 판정 | ||
| if (firstRight != secondLeft) { | ||
| affectedInfo[0].add(1) | ||
| affectedInfo[1].add(0) | ||
| } | ||
| if (secondRight != thirdLeft) { | ||
| affectedInfo[1].add(2) | ||
| affectedInfo[2].add(1) | ||
| } | ||
| if (thirdRight != fourthLeft) { | ||
| affectedInfo[2].add(3) | ||
| affectedInfo[3].add(2) | ||
| } |
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val gearList = Array(4) {
Gear(readln())
}.toList()
val affectedInfo = Array(4) {
mutableListOf<Int>()
}
fun solution() {
val rotateCnt = readln().toInt()
val rotateInfoList = Array(rotateCnt) {
val (gearNum, dir) = readln().split(" ").map { it.toInt() }
RotateInfo(gearNum, dir)
}
rotateInfoList.forEach { rotateInfo ->
val (gearNum, dir) = rotateInfo
gearList.windowed(2, 1).forEachIndexed { index, gears ->
val (prev, next) = gears.map { it.getPole() }
if (prev.second != next.first) {
affectedInfo[index].add(index + 1)
affectedInfo[index + 1].add(index)
}
}어... 이런거 있을거같은데? 찾아보면 있더라구요!
머리를 쓰지 않으면 고생합니다 ㅠ
저도
windowed같은게 있는지 몰랐어요
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| var score = 0 | ||
| repeat(4) { cnt -> | ||
| score += gearList[cnt].getTopState() * twoToPowOfExponent(cnt) | ||
| } |
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이건 이제 안할때 된거같지만
val score = gearList.mapIndexed { index, gear ->
gear.getTopState() * twoToPowOfExponent(index)
}.sum()택 1
val score = (0 until 4).sumOf { gearList[it].getTopState() * twoToPowOfExponent(it) }|
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| val rootQueue: Queue<Int> = ArrayDeque() | ||
| val nodeCnt = readln().toInt() | ||
| val treeArray = Array(nodeCnt + 1) { mutableListOf<Int>() } |
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중첩되지 않고 사실 순서보다는 실제 Collection의 값을 삭제하는 데에 초점을 맞췄게 때문에
mutableList 보다는 mutableSet 사용하시는게 이 로직에서는 훨씬 효율적이에요!
| treeArray[curParent].forEach { child -> | ||
| parentNodeData[child] = curParent | ||
| // 방문 판정 -> 자식 노드에서 부모 노드 제거 | ||
| treeArray[child].remove(curParent) |
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MutableSet이면 더 효율적으로 삭제될 수 있는 이유
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| val meetingList = mutableListOf<MeetingData>() | ||
| var canMeetingCnt = 0 | ||
| var endTime = 0 | ||
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| repeat(meetingCnt) { | ||
| val (start, end) = readln().split(" ").map { it.toInt() } | ||
| meetingList.add(MeetingData(start, end)) | ||
| } | ||
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| // 정렬 | ||
| meetingList.sortWith(compareBy<MeetingData> { it.end }.thenBy { it.start }) |
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소팅을 통해 추가해야 하는 경우에는 PriorityQueue를 이용해봐요
이럴때 쓰라고 만들어진 친구입니다!
val pq = PriorityQueue(compareBy<MeetingData> { it.end }.thenBy { it.start })
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| endTime = meetingList.first().end | ||
| canMeetingCnt++ | ||
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| meetingList.drop(1).forEach { meetingData -> | ||
| if (endTime <= meetingData.start) { | ||
| endTime = meetingData.end | ||
| canMeetingCnt++ | ||
| } | ||
| } |
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pq를 사용하면 drop 처리 안하고 그냥 뽑아주면 되겠죠?
endTime = pq.poll().end
canMeetingCnt++
while (pq.isNotEmpty()) {
val meetingData = pq.poll()
if (endTime <= meetingData.start) {
endTime = meetingData.end
canMeetingCnt++
}
}| val meetingCnt = readln().toInt() | ||
| val meetingList = mutableListOf<MeetingData>() | ||
| var canMeetingCnt = 0 | ||
| var endTime = 0 |
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항상 전역변수를 선언해줘야한다는 부분을 사용하는 부분에만 적용한다 생각해보시면 아래 endTime을 사용하는 부분에서 var 선언해주면 되지 않았을까 싶어요!
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Issue Number
Issue #17
💎 문제 해결
🔥 특이사항/질문
자유롭게 작성해주세요!
오호... 별건 아니지만... dp문제 거의 처음으로 혼자 풀어봐서 기쁘네요,,,