[Kotlin] Korean Coding Test - Programmers - Getting Reported Results

2023-09-05

Question

Each user can report one user at a time.

There is no limit to the number of reports.You can continue to report different users.
You can report one user multiple times, but the number of reports for the same user is treated as one time.

Users who have been reported more than k times will be suspended from using the bulletin board, and the suspension will be mailed to all users who reported the user.

We collect all the information that the user reported and send a suspension email at the end while suspending the bulletin board at once.

Restrictions

The element of id_list is a string that represents the user's id and consists of only lowercase letters.
The id_list does not contain the same ID in duplicate.
The element of the report is a string with only lowercase letters in the form of "user_id reported_id".
User id and reported id are separated by one space.
You don't report yourself.
The array to be returned can contain the number of mails received by each user in the order of id in the id_list.

Input/Output Example

Input/Output Example #1

Input
id_list: ["muzi", "frodo", "apeach", "neo"]
report: ["muzi frodo","apeach frodo","frodo neo","muzi neo","apeach muzi"]
k: 2
Output [2,1,1,0]

Input/Output Example #2

Input
id_list: ["con", "ryan"]
report: ["ryan con", "ryan con", "ryan con", "ryan con"]
k: 3
Output : [0,0]

Time limit

Accuracy test: 10 seconds

Code 1

Kotlin

class Solution {
    fun solution(idList: Array<String>, report: Array<String>, k: Int): IntArray {
        // Reported details - cannot be duplicated
        val targetReport = mutableMapOf<String, MutableSet<String>>()
        // If distinct() is used, both List and Set take at least 29 seconds, but if you use Set without distinct, it takes at least 12 seconds
        report.forEach {
            val (reporter, target) = it.split(" ")
            targetReport[target] = targetReport.getOrDefault(target, mutableSetOf())
            targetReport[target]?.add(reporter)
        }

        // Mail history
        val userSendMail = mutableMapOf<String, Int>()
        // Mail the suspension to all users who reported the user
        targetReport
            .filter { it.value.count() >= k }
            .forEach {
                it.value.forEach { userId ->
                    userSendMail[userId] = userSendMail.getOrDefault(userId, 0) + 1
                }
            }
        return idList.map { userSendMail.getOrDefault(it, 0) }.toIntArray()
    }
}

Plain Text

TEST 1 〉	Pass (13.21ms, 61.5MB)
TEST 2 〉	Pass (13.10ms, 62.1MB)
TEST 3 〉	Pass (154.73ms, 143MB)
TEST 4 〉	Pass (12.99ms, 62.2MB)
TEST 5 〉	Pass (14.77ms, 62.3MB)
TEST 6 〉	Pass (23.58ms, 64.5MB)
TEST 7 〉	Pass (20.77ms, 70.6MB)
TEST 8 〉	Pass (44.83ms, 84.6MB)
TEST 9 〉	Pass (126.78ms, 111MB)
TEST 10 〉	Pass (95.07ms, 117MB)
TEST 11 〉	Pass (161.39ms, 150MB)
TEST 12 〉	Pass (16.92ms, 61.9MB)
TEST 13 〉	Pass (18.50ms, 62MB)
TEST 14 〉	Pass (139.77ms, 119MB)
TEST 15 〉	Pass (170.33ms, 148MB)
TEST 16 〉	Pass (14.17ms, 62.9MB)
TEST 17 〉	Pass (22.37ms, 62MB)
TEST 18 〉	Pass (20.16ms, 62.7MB)
TEST 19 〉	Pass (26.16ms, 62.4MB)
TEST 20 〉	Pass (113.04ms, 116MB)
TEST 21 〉	Pass (211.26ms, 141MB)
TEST 22 〉	Pass (12.85ms, 61.2MB)
TEST 23 〉	Pass (12.81ms, 62.1MB)
TEST 24 〉	Pass (13.11ms, 61.2MB)

Code 2

Kotlin

  class Solution {
    fun solution(idList: Array<String>, report: Array<String>, k: Int): IntArray =
        report.distinct() // Remove duplicate declaration
            .map { it.split(" ") }
            .groupBy { it[1] } // Reported details by user
            .filter { it.value.size >= k } // Report history k cases or more
            .map { a -> a.value.map { it[0] } } // Reporter extraction
            .flatten() // Ungroup
            .groupingBy { it }.eachCount()
            .run { idList.map { getOrDefault(it, 0) } }.toIntArray()
}

Plain Text

TEST 1 〉	Pass (35.51ms, 65.4MB)
TEST 2 〉	Pass (28.79ms, 65.3MB)
TEST 3 〉      Pass (31.91ms, 65.8MB)
TEST 5 〉	Pass (44.67ms, 65.6MB)
TEST 6 〉	Pass (40.54ms, 65.4MB)
TEST 7 〉	Pass (39.13ms, 72.6MB)
TEST 8 〉	Pass (39.47ms, 83.5MB)
TEST 9 〉	Pass (150.46ms, 131MB)
TEST 10 〉	Pass (101.38ms, 113MB)
TEST 11 〉	Pass (234.00ms, 179MB)
TEST 12 〉	Pass (35.69ms, 67MB)
TEST 13 〉	Pass (41.59ms, 65.5MB)
TEST 14 〉	Pass (139.25ms, 119MB)
TEST 15 〉	Pass (130.72ms, 130MB)
TEST 16 〉	Pass (30.91ms, 66.7MB)
TEST 17 〉	Pass (34.17ms, 66MB)
TEST 18 〉	Pass (40.42ms, 66MB)
TEST 19 〉	Pass (49.65ms, 66.5MB)
TEST 20 〉	Pass (124.52ms, 116MB)
TEST 21 〉	Pass (175.12ms, 128MB)
TEST 22 〉	Pass (29.46ms, 64.8MB)
TEST 23 〉	Pass (30.37ms, 65.5MB)
TEST 24 〉	Pass (30.01ms, 65.4MB)