LeetCode in Kotlin

1604. Alert Using Same Key-Card Three or More Times in a One Hour Period

Medium

LeetCode company workers use key-cards to unlock office doors. Each time a worker uses their key-card, the security system saves the worker’s name and the time when it was used. The system emits an alert if any worker uses the key-card three or more times in a one-hour period.

You are given a list of strings keyName and keyTime where [keyName[i], keyTime[i]] corresponds to a person’s name and the time when their key-card was used in a single day.

Access times are given in the 24-hour time format “HH:MM”, such as "23:51" and "09:49".

Return a list of unique worker names who received an alert for frequent keycard use. Sort the names in ascending order alphabetically.

Notice that "10:00" - "11:00" is considered to be within a one-hour period, while "22:51" - "23:52" is not considered to be within a one-hour period.

Example 1:

Input: keyName = [“daniel”,”daniel”,”daniel”,”luis”,”luis”,”luis”,”luis”], keyTime = [“10:00”,”10:40”,”11:00”,”09:00”,”11:00”,”13:00”,”15:00”]

Output: [“daniel”]

Explanation: “daniel” used the keycard 3 times in a one-hour period (“10:00”,”10:40”, “11:00”).

Example 2:

Input: keyName = [“alice”,”alice”,”alice”,”bob”,”bob”,”bob”,”bob”], keyTime = [“12:01”,”12:00”,”18:00”,”21:00”,”21:20”,”21:30”,”23:00”]

Output: [“bob”]

Explanation: “bob” used the keycard 3 times in a one-hour period (“21:00”,”21:20”, “21:30”).

Constraints:

• 1 <= keyName.length, keyTime.length <= 105
• keyName.length == keyTime.length
• keyTime[i] is in the format “HH:MM”.
• [keyName[i], keyTime[i]] is unique.
• 1 <= keyName[i].length <= 10
• keyName[i] contains only lowercase English letters.

Solution

class Solution {
    fun alertNames(keyName: Array<String>, keyTime: Array<String>): List<String> {
        val map = HashMap<String, MutableList<String>>()
        for (i in keyName.indices) {
            map.putIfAbsent(keyName[i], ArrayList())
            map[keyName[i]]!!.add(keyTime[i])
        }
        val soln: MutableList<String> = ArrayList()
        for ((key, timeStamps) in map) {
            timeStamps.sort()
            var i = 0
            while (i + 2 < timeStamps.size) {
                val first = timeStamps[i].split(":").dropLastWhile { it.isEmpty() }.toTypedArray()
                val third = timeStamps[i + 2].split(":").dropLastWhile { it.isEmpty() }.toTypedArray()
                val hourDiff = third[0].toInt() - first[0].toInt()
                val minDiff = third[1].toInt() - first[1].toInt()
                if (hourDiff == 0 || hourDiff == 1 && minDiff <= 0) {
                    soln.add(key)
                    break
                }
                i++
            }
        }
        soln.sort()
        return soln
    }
}

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