LeetCode-in-Java
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
public class Solution {
public int minDifficulty(int[] jobDifficulty, int d) {
int totalJobs = jobDifficulty.length;
if (totalJobs < d) {
return -1;
}
int maxJobsOneDay = totalJobs - d + 1;
int[] map = new int[totalJobs];
int maxDiff = Integer.MIN_VALUE;
for (int k = totalJobs - 1; k > totalJobs - 1 - maxJobsOneDay; k--) {
maxDiff = Math.max(maxDiff, jobDifficulty[k]);
map[k] = maxDiff;
}
for (int day = d - 1; day > 0; day--) {
int maxEndIndex = (totalJobs - 1) - (d - day);
int maxStartIndex = maxEndIndex - maxJobsOneDay + 1;
for (int startIndex = maxStartIndex; startIndex <= maxEndIndex; startIndex++) {
map[startIndex] = Integer.MAX_VALUE;
int maxDiffOfTheDay = Integer.MIN_VALUE;
for (int endIndex = startIndex; endIndex <= maxEndIndex; endIndex++) {
maxDiffOfTheDay = Math.max(maxDiffOfTheDay, jobDifficulty[endIndex]);
int totalDiff = maxDiffOfTheDay + map[endIndex + 1];
map[startIndex] = Math.min(map[startIndex], totalDiff);
}
}
}
return map[0];
}
}