Was broadly asked 2 questions which were easy enough but the question was too convoluted to understand the context and answer in a short while. Was given less than 40 minutes. The first question given was to correct the code to pass the test cases. It was mostly a data type fix, the timestamp was a string initially, after changing it to float, the test cases worked. Second question was to write a function to count the total journey of all the users. The interview ended before I could complete the function. ``` import static org.junit.Assert.assertEquals; import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; import java.util.*; /* We are writing software to analyze logs for toll booths on a highway. This highway is a divided highway with limited access; the only way on to or off of the highway is through a toll booth. There are three types of toll booths: * ENTRY (E in the diagram) toll booths, where a car goes through a booth as it enters the highway. * EXIT (X in the diagram) toll booths, where a car goes through a booth as it exits the highway. * MAINROAD (M in the diagram), which have sensors that record a license plate as a car drives through at full speed. Exit Booth Entry Booth | | X E \ / ---<------------<---------M---------<-----------<---------<---- (West-bound side) =============================================================== (East-bound side) ------>--------->---------M--------->--------->--------->------ / \ E X | | Entry Booth Exit Booth */ /* We are interested in how many people are using the highway, and so we would like to count how many complete journeys are taken in the log file. A complete journey consists of: * A driver entering the highway through an ENTRY toll booth. * The driver passing through some number of MAINROAD toll booths (possibly 0). * The driver exiting the highway through an EXIT toll booth. For example, the following excerpt of log lines contains complete journeys for the cars with JOX304 and THX138: . . . 90750.191 JOX304 250E ENTRY 91081.684 JOX304 260E MAINROAD 91082.101 THX138 110E ENTRY 91483.251 JOX304 270E MAINROAD 91873.920 THX138 120E MAINROAD 91874.493 JOX304 280E EXIT . . 91982.102 THX138 290E EXIT 92301.302 THX138 300E ENTRY 92371.302 THX138 310E EXIT . ``` 2-1) Write a function in LogFile named countJourneys() that returns how many complete journeys there are in the given LogFile. */ ``` class LogEntry { /** * Represents an entry from a single log line. Log lines look like this in the file: * * 34400.409 SXY288 210E ENTRY * * Where: * * 34400.409 is the timestamp in seconds since the software was started. * * SXY288 is the license plate of the vehicle passing through the toll booth. * * 210E is the location and traffic direction of the toll booth. Here, the toll * booth is at 210 kilometers from the start of the tollway, and the E indicates * that the toll booth was on the east-bound traffic side. Tollbooths are placed * every ten kilometers. * * ENTRY indicates which type of toll booth the vehicle went through. This is one of * "ENTRY", "EXIT", or "MAINROAD". **/ private final float timestamp; private final String licensePlate; private final String boothType; private final int location; private final String direction; public LogEntry(String logLine) { String[] tokens = logLine.split(" "); this.timestamp = Float.parseFloat(tokens[0]); this.licensePlate = tokens[1]; this.boothType = tokens[3]; this.location = Integer.parseInt(tokens[2].substring(0, tokens[2].length() - 1)); String directionLetter = tokens[2].substring(tokens[2].length() - 1); if (directionLetter.equals("E")) { this.direction = "EAST"; } else if (directionLetter.equals("W")) { this.direction = "WEST"; } else { throw new IllegalArgumentException(); } } public float getTimestamp() { return timestamp; } public String getLicensePlate() { return licensePlate; } public String getBoothType() { return boothType; } public int getLocation() { return location; } public String getDirection() { return direction; } @Override public String toString() { return String.format( "", timestamp, licensePlate, location, direction, boothType ); } } class LogFile { /* * Represents a file containing a number of log lines, converted to LogEntry * objects. */ List logEntries; public LogFile(BufferedReader reader) throws IOException { this.logEntries = new ArrayList<>(); String line = reader.readLine(); while (line != null) { LogEntry logEntry = new LogEntry(line.strip()); this.logEntries.add(logEntry); line = reader.readLine(); } } // // HashMap<>(); // entry Hashmap // { // "JOX304" -> "1", // "THX138" -> "2", // } // exit Hashmap // { // "Jox" -> 1, // "THX138" -> "2", // } public int countJourneys() { Map entryMap = new HashMap<>(); Map exitMap = new HashMap<>(); for(LogEntry singleLog: this.logEntries) { String singleBoothType = singleLog.getBoothType(); String licensePlate = singleLog.getLicensePlate(); if(singleBoothType == "ENTRY") { entryMap.put(licensePlate, entryMap.getOrDefault(licensePlate, 0) + 1); } else if(singleBoothType == "EXIT") { exitMap.put(licensePlate, entryMap.getOrDefault(licensePlate, 0) + 1); } } int totalCount = 0; for(Map.Entry entry : entryMap.entrySet()) { String singleLicensePlate = entry.getKey(); int count = entry.getValue(); if(exitMap.containsKey(singleLicensePlate)) { totalCount += exitMap.get(singleLicensePlate); } } return totalCount; } public LogEntry get(int index) { return this.logEntries.get(index); } public int size() { return this.logEntries.size(); } } public class Solution { public static void main(String[] argv) throws IOException { System.out.println("executing main"); testLogFile(); testLogEntry(); testCountJourneys(); } public static void testLogFile() throws IOException { System.out.println("Running testLogFile"); try ( BufferedReader reader = new BufferedReader( new FileReader("/content/test/tollbooth_small.log") ); ) { LogFile logFile = new LogFile(reader); assertEquals(13, logFile.size()); for (LogEntry entry : logFile.logEntries) { assert (entry instanceof LogEntry); } } } public static void testLogEntry() { System.out.println("Running testLogEntry"); String logLine = "44776.619 KTB918 310E MAINROAD"; LogEntry logEntry = new LogEntry(logLine); System.out.println("line 166"); System.out.printf("timestamp is %s\n", logEntry.getTimestamp()); assertEquals(44776.619f, logEntry.getTimestamp(), 0.0001); assertEquals("KTB918", logEntry.getLicensePlate()); assertEquals(310, logEntry.getLocation()); assertEquals("EAST", logEntry.getDirection()); assertEquals("MAINROAD", logEntry.getBoothType()); logLine = "52160.132 ABC123 400W ENTRY"; logEntry = new LogEntry(logLine); assertEquals(52160.132f, logEntry.getTimestamp(), 0.0001); assertEquals("ABC123", logEntry.getLicensePlate()); assertEquals(400, logEntry.getLocation()); assertEquals("WEST", logEntry.getDirection()); assertEquals("ENTRY", logEntry.getBoothType()); } public static void testCountJourneys() throws IOException { System.out.println("Running testCountJourneys"); try (BufferedReader reader = new BufferedReader(new FileReader("/content/test/tollbooth_small.log"))) { LogFile logFile = new LogFile(reader); assertEquals(3, logFile.countJourneys()); } try (BufferedReader reader = new BufferedReader(new FileReader("/content/test/tollbooth_medium.log"))) { LogFile logFile = new LogFile(reader); assertEquals(63, logFile.countJourneys()); } } } ```