[Solved] Task Scheduler II LeetCode Contest

You are given a 0-indexed array of positive integers tasks, representing tasks that need to be completed in order, where tasks[i] represents the type of the ith task.

You are also given a positive integer space, which represents the minimum number of days that must pass after the completion of a task before another task of the same type can be performed.

Each day, until all tasks have been completed, you must either:

• Complete the next task from tasks, or
• Take a break.

Return the minimum number of days needed to complete all tasks.

Task Scheduler II LeetCode Contest

Example 1:

Input: tasks = [1,2,1,2,3,1], space = 3
Output: 9
Explanation:
One way to complete all tasks in 9 days is as follows:
Day 1: Complete the 0th task.
Day 2: Complete the 1st task.
Day 3: Take a break.
Day 4: Take a break.
Day 5: Complete the 2nd task.
Day 6: Complete the 3rd task.
Day 7: Take a break.
Day 8: Complete the 4th task.
Day 9: Complete the 5th task.
It can be shown that the tasks cannot be completed in less than 9 days.

Example 2:

Input: tasks = [5,8,8,5], space = 2
Output: 6
Explanation:
One way to complete all tasks in 6 days is as follows:
Day 1: Complete the 0th task.
Day 2: Complete the 1st task.
Day 3: Take a break.
Day 4: Take a break.
Day 5: Complete the 2nd task.
Day 6: Complete the 3rd task.
It can be shown that the tasks cannot be completed in less than 6 days.

Constraints:

• 1 <= tasks.length <= 105
• 1 <= tasks[i] <= 109
• 1 <= space <= tasks.length

Solution

    public long taskSchedulerII(int[] tasks, int space) {
        Map<Integer, Long> last = new HashMap<>();;
        long res = 0;
        for (int a : tasks)
            if (last.containsKey(a))
                last.put(a, res = Math.max(res, last.get(a) + space) + 1);
            else
                last.put(a, ++res);
        return res;
    }

    long long taskSchedulerII(vector<int>& tasks, int space) {
        unordered_map<int, long long> last;
        long long res = 0;
        for (int a: tasks)
            if (last.count(a))
                last[a] = res = max(res, last[a] + space) + 1;
            else
                last[a] = ++res;
        return res;
    }

    def taskSchedulerII(self, A, space):
        last = defaultdict(lambda: - len(A) - 10)
        res = 0
        for a in A:
            last[a] = res = max(res, last[a] + space) + 1
        return res

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