Problème
With async/await you can start several tasks and let them run at the same time. A SemaphoreSlim often caps how many run at once.
Tasks numbered 0 to n − 1 take durations[i] time units. At time 0 start as many tasks as the limit allows, in index order. Whenever tasks finish, record them (if several finish at the same moment, lower index first) and immediately start the next waiting tasks, in index order, to fill the free slots.
Implement parallel_task_order(durations, limit).
Input
durations: How long each task takes.
limit: The maximum number of tasks running at the same time.
Output
Return the task indices in the order they finish.
Contraintes
1 ≤ n ≤ 100,000
1 ≤ durations[i] ≤ 10^6; 1 ≤ limit ≤ n
Exemples
Entrée :
limit = 2
durations = [4, 2, 3, 1]
Sortie attendue :
expected = [1, 0, 2, 3]Entrée :
long long limit = 2;
std::vector<long long> durations = {4, 2, 3, 1};
Sortie attendue :
std::vector<long long> expected = {1, 0, 2, 3};Entrée :
long limit = 2;
long[] durations = new long[] {4, 2, 3, 1};
Sortie attendue :
long[] expected = new long[] {1, 0, 2, 3};Explication
Tasks 0 and 1 start. Task 1 ends at 2 and task 2 starts (ends at 5). Task 0 ends at 4 and task 3 starts (ends at 5). Tasks 2 and 3 finish together, lower index first: [1, 0, 2, 3].
Entrée :
limit = 3
durations = [3, 1, 2]
Sortie attendue :
expected = [1, 2, 0]Entrée :
long long limit = 3;
std::vector<long long> durations = {3, 1, 2};
Sortie attendue :
std::vector<long long> expected = {1, 2, 0};Entrée :
long limit = 3;
long[] durations = new long[] {3, 1, 2};
Sortie attendue :
long[] expected = new long[] {1, 2, 0};Explication
All tasks run at once and finish at 1, 2 and 3: [1, 2, 0].
Comment l'aborder
Essayez d'abord seul, puis ouvrez les indices un par un.
Indice 1
Keep the running tasks ordered by finish time, then by index.
Indice 2
Each step jumps to the next finish time and collects every task ending then.
Indice 3
Refill free slots with the next waiting tasks in index order.
Complexité attendue
O(n log limit) time, O(limit) extra space
Références
Ce défi a été adapté pour CodeUtility. Suivez l'énoncé et les contraintes ci-dessus.