LeetCode in Kotlin
1335. Minimum Difficulty of a Job Schedule
Hard
You want to schedule a list of jobs in d days. Jobs are dependent (i.e To work on the ith job, you have to finish all the jobs j where 0 <= j < i).
You have to finish at least one task every day. The difficulty of a job schedule is the sum of difficulties of each day of the d days. The difficulty of a day is the maximum difficulty of a job done on that day.
You are given an integer array jobDifficulty and an integer d. The difficulty of the ith job is jobDifficulty[i].
Return the minimum difficulty of a job schedule. If you cannot find a schedule for the jobs return -1.
Example 1:
Input: jobDifficulty = [6,5,4,3,2,1], d = 2
Output: 7
Explanation: First day you can finish the first 5 jobs, total difficulty = 6.
Second day you can finish the last job, total difficulty = 1.
The difficulty of the schedule = 6 + 1 = 7
Example 2:
Input: jobDifficulty = [9,9,9], d = 4
Output: -1
Explanation: If you finish a job per day you will still have a free day. you cannot find a schedule for the given jobs.
Example 3:
Input: jobDifficulty = [1,1,1], d = 3
Output: 3
Explanation: The schedule is one job per day. total difficulty will be 3.
Constraints:
1 <= jobDifficulty.length <= 3000 <= jobDifficulty[i] <= 10001 <= d <= 10
Solution
class Solution {
fun minDifficulty(jobDifficulty: IntArray, d: Int): Int {
val totalJobs = jobDifficulty.size
if (totalJobs < d) {
return -1
}
val maxJobsOneDay = totalJobs - d + 1
val map = IntArray(totalJobs)
var maxDiff = Int.MIN_VALUE
for (k in totalJobs - 1 downTo totalJobs - 1 - maxJobsOneDay + 1) {
maxDiff = Math.max(maxDiff, jobDifficulty[k])
map[k] = maxDiff
}
for (day in d - 1 downTo 1) {
val maxEndIndex = totalJobs - 1 - (d - day)
val maxStartIndex = maxEndIndex - maxJobsOneDay + 1
for (startIndex in maxStartIndex..maxEndIndex) {
map[startIndex] = Int.MAX_VALUE
var maxDiffOfTheDay = Int.MIN_VALUE
for (endIndex in startIndex..maxEndIndex) {
maxDiffOfTheDay = Math.max(maxDiffOfTheDay, jobDifficulty[endIndex])
val totalDiff = maxDiffOfTheDay + map[endIndex + 1]
map[startIndex] = Math.min(map[startIndex], totalDiff)
}
}
}
return map[0]
}
}