_1396.java

packagecom.fishercoder.solutions.secondthousand;

importjava.util.HashMap;
importjava.util.LinkedList;
importjava.util.Map;

publicclass_1396 {
publicstaticclassSolution1 {
publicclassUndergroundSystem {

classStationAndTime {
StringstationName;
intt;

publicStationAndTime(StringstationName, intt) {
this.stationName = stationName;
this.t = t;
 }

publicStringgetStation() {
returnthis.stationName;
 }

publicintgetTime() {
returnthis.t;
 }
 }

Map<String, double[]> averageTimeMap;
Map<Integer, LinkedList<StationAndTime>> travelerMap = newHashMap<>();

publicUndergroundSystem() {
averageTimeMap = newHashMap<>();
travelerMap = newHashMap<>();
 }

publicvoidcheckIn(intid, StringstationName, intt) {
if (!travelerMap.containsKey(id)) {
travelerMap.put(id, newLinkedList<>());
 }
travelerMap.get(id).add(newStationAndTime(stationName, t));
 }

publicvoidcheckOut(intid, StringstationName, intt) {
LinkedList<StationAndTime> list = travelerMap.get(id);
StationAndTimestationAndTime = list.getLast();
StringstartToEndStation = stationAndTime.getStation() + "->" + stationName;
intduration = t - stationAndTime.getTime();
if (!averageTimeMap.containsKey(startToEndStation)) {
averageTimeMap.put(startToEndStation, newdouble[] {duration, 1});
 } else {
double[] pair = averageTimeMap.get(startToEndStation);
doublenewAverage =
 (double) (pair[0] * pair[1] + duration) / (double) (pair[1] + 1);
averageTimeMap.put(startToEndStation, newdouble[] {newAverage, pair[1] + 1});
 }
 }

publicdoublegetAverageTime(StringstartStation, StringendStation) {
returnaverageTimeMap.get(startStation + "->" + endStation)[0];
 }
 }
 }
}