621_Task_Scheduler.java

classSolution {
publicintleastInterval(char[] tasks, intn) {
if (tasks == null || tasks.length == 0) {
return0;
 }

Map<Character, Integer> hm = newHashMap<>();
PriorityQueue<Map.Entry<Character, Integer>> pq = newPriorityQueue<>(
 (pair1, pair2) -> pair2.getValue() - pair1.getValue());

for (charc : tasks) {
hm.put(c, hm.getOrDefault(c, 0) + 1);
 }
pq.addAll(hm.entrySet());

intcycles = 0;

while (!pq.isEmpty()) {
List<Map.Entry<Character, Integer>> temp = newArrayList<>();
intemptyTaskSlots = n + 1;

while (emptyTaskSlots > 0 && !pq.isEmpty()) {
 --emptyTaskSlots;
 ++cycles;

Map.Entry<Character, Integer> entry = pq.poll();
entry.setValue(entry.getValue() - 1);

if (entry.getValue() > 0) {
temp.add(entry);
 }
 }

pq.addAll(temp);

if (pq.isEmpty()) {
break;
 }

cycles += emptyTaskSlots;
 }

returncycles;
 }
}