TT0.java

importjava.util.*;

publicclassTT0 {
// Epoch timestamp with list of users who had an action for the respective
// timestamp
privateTreeMap<Integer, Set<Integer>> logs;

publicTT0() {
logs = newTreeMap<>();
 }

publicvoidput(intid, inttimestamp) {
logs.putIfAbsent(timestamp, newHashSet<>());
logs.get(timestamp).add(id);
 }

publicList<Integer> retrieve(inttotalMinutes, intintervalLength) {
List<Integer> result = newArrayList<>();

intintervalStart = 0, intervalEnd = intervalStart + intervalLength;

while (intervalStart <= totalMinutes) {
intend = Math.min(totalMinutes, intervalEnd + 1);
SortedMap<Integer, Set<Integer>> submap = logs.subMap(intervalStart, end);
result.add(submap.size());

intervalStart += intervalLength;
intervalEnd += intervalLength;
 }

returnresult;
 }

publicstaticvoidmain(String[] args) {
/*
 * [1, 1518290973] [1, 1518291096] [1, 1518291200] [1, 1518291200] [2,
 * 1518291032] [3, 1518291095] [3, 1518291178] [4, 1518291120]
 * 
 * 1 -> 3 minutes in total 2 -> 1 minutes in total 3 -> 2 minutes in total 4 ->
 * 1 minutes in total
 * 
 * 2 users spend 0-1 minutes in total - users 2 and 4 2 users spend 2-3 minutes
 * in total - users 1 and 3
 */
int[][] logs = newint[][] { { 1, 1518290973 }, { 2, 1518291032 }, { 3, 1518291095 }, { 1, 1518291096 },
 { 4, 1518291120 }, { 3, 1518291178 }, { 1, 1518291200 }, { 1, 1518291200 } };

TT0logRetrieval = newTT0();

for (int[] log : logs) {
logRetrieval.put(log[0], log[1]);
 }

for (intinterval : logRetrieval.retrieve(1, 2)) {
System.out.print(interval + ", ");
 }

System.out.println();

return;
 }
}