Ported 79. Slalom to Java.

Also, documented one possible bug in the orignal program.

79_Slalom/README.md

@@ -14,3 +14,11 @@ As published in Basic Computer Games (1978):
 
 Downloaded from Vintage Basic at
 http://www.vintage-basic.net/games.html
+
+### Bugs
+
+- In the original version, the data pointer doesn't reset after a race is completed. This causes subsequent races to 
+error at some future point at line 540,
+
+      540    READ Q
+

79_Slalom/java/Slalom.java

@@ -0,0 +1,373 @@
+import java.util.Arrays;
+import java.util.InputMismatchException;
+import java.util.Random;
+import java.util.Scanner;
+
+/**
+ * Slalom
+ * <p>
+ * Converted from BASIC to Java by Aldrin Misquitta (@aldrinm)
+ *
+ * There is a bug in the original version where the data pointer doesn't reset after a race is completed. This causes subsequent races to error at
+ * some future point on line "540    READ Q"
+ */
+public class Slalom {
+
+    private static final int MAX_NUM_GATES = 25;
+    private static final int[] MAX_SPEED = {
+            14, 18, 26, 29, 18,
+            25, 28, 32, 29, 20,
+            29, 29, 25, 21, 26,
+            29, 20, 21, 20, 18,
+            26, 25, 33, 31, 22
+    };
+
+    public static void main(String[] args) {
+        var random = new Random();
+
+        printIntro();
+        Scanner scanner = new Scanner(System.in);
+
+        int numGates = readNumberOfGatesChoice(scanner);
+
+        printMenu();
+        MenuChoice menuChoice;
+        do {
+            menuChoice = readMenuOption(scanner);
+            switch (menuChoice) {
+                case INS:
+                    printInstructions();
+                    break;
+                case MAX:
+                    printApproxMaxSpeeds(numGates);
+                    break;
+                case RUN:
+                    run(numGates, scanner, random);
+                    break;
+            }
+        } while (menuChoice != MenuChoice.RUN);
+    }
+
+    private static void run(int numGates, Scanner scan, Random random) {
+        int rating = readSkierRating(scan);
+        boolean gameInProgress = true;
+        var medals = new Medals(0, 0, 0);
+
+        while (gameInProgress) {
+            System.out.println("THE STARTER COUNTS DOWN...5...4...3...2...1...GO!");
+            System.out.println("YOU'RE OFF!");
+
+            int speed = random.nextInt(18 - 9) + 9;
+
+            float totalTimeTaken = 0;
+            try {
+                totalTimeTaken = runThroughGates(numGates, scan, random, speed);
+                System.out.printf("%nYOU TOOK %.2f SECONDS.%n", totalTimeTaken + random.nextFloat());
+
+                medals = evaluateAndUpdateMedals(totalTimeTaken, numGates, rating, medals);
+            } catch (WipedOutOrSnaggedAFlag | DisqualifiedException e) {
+                //end of this race! Print time taken and stop
+                System.out.printf("%nYOU TOOK %.2f SECONDS.%n", totalTimeTaken + random.nextFloat());
+            }
+
+            gameInProgress = readRaceAgainChoice(scan);
+        }
+
+        System.out.println("THANKS FOR THE RACE");
+        if (medals.getGold() >= 1) System.out.printf("GOLD MEDALS: %d%n", medals.getGold());
+        if (medals.getSilver() >= 1) System.out.printf("SILVER MEDALS: %d%n", medals.getSilver());
+        if (medals.getBronze() >= 1) System.out.printf("BRONZE MEDALS: %d%n", medals.getBronze());
+    }
+
+    private static Medals evaluateAndUpdateMedals(float totalTimeTaken, int numGates, int rating,
+                                                  Medals medals) {
+        var m = totalTimeTaken;
+        m = m / numGates;
+        int goldMedals = medals.getGold();
+        int silverMedals = medals.getSilver();
+        int bronzeMedals = medals.getBronze();
+        if (m < 1.5 - (rating * 0.1)) {
+            System.out.println("YOU WON A GOLD MEDAL!");
+            goldMedals++;
+        } else if (m < 2.9 - rating * 0.1) {
+            System.out.println("YOU WON A SILVER MEDAL");
+            silverMedals++;
+        } else if (m < 4.4 - rating * 0.01) {
+            System.out.println("YOU WON A BRONZE MEDAL");
+            bronzeMedals++;
+        }
+        return new Medals(goldMedals, silverMedals, bronzeMedals);
+    }
+
+    /**
+     * @return the total time taken through all the gates.
+     */
+    private static float runThroughGates(int numGates, Scanner scan, Random random, int speed) throws DisqualifiedException, WipedOutOrSnaggedAFlag {
+        float totalTimeTaken = 0.0f;
+        for (int i = 0; i < numGates; i++) {
+            var gateNum = i + 1;
+            boolean stillInRace = true;
+            boolean gateCompleted = false;
+            while (!gateCompleted) {
+                System.out.printf("%nHERE COMES GATE # %d:%n", gateNum);
+                printSpeed(speed);
+
+                var tmpSpeed = speed;
+
+                int chosenOption = readOption(scan);
+                switch (chosenOption) {
+                    case 0:
+                        //how long
+                        printHowLong(totalTimeTaken, random);
+                        break;
+                    case 1:
+                        //speed up a lot
+                        speed = speed + random.nextInt(10 - 5) + 5;
+                        break;
+                    case 2:
+                        //speed up a little
+                        speed = speed + random.nextInt(5 - 3) + 3;
+                        break;
+                    case 3:
+                        //speed up a teensy
+                        speed = speed + random.nextInt(4 - 1) + 1;
+                        break;
+                    case 4:
+                        //keep going at the same speed
+                        break;
+                    case 5:
+                        //check a teensy
+                        speed = speed - random.nextInt(4 - 1) + 1;
+                        break;
+                    case 6:
+                        //check a little
+                        speed = speed - random.nextInt(5 - 3) + 3;
+                        break;
+                    case 7:
+                        //check a lot
+                        speed = speed - random.nextInt(10 - 5) + 5;
+                        break;
+                    case 8:
+                        //cheat
+                        System.out.println("***CHEAT");
+                        if (random.nextFloat() < 0.7) {
+                            System.out.println("AN OFFICIAL CAUGHT YOU!");
+                            stillInRace = false;
+                        } else {
+                            System.out.println("YOU MADE IT!");
+                            totalTimeTaken = totalTimeTaken + 1.5f;
+                        }
+                        break;
+                }
+
+                if (stillInRace) {
+                    printSpeed(speed);
+                    stillInRace = checkAndProcessIfOverMaxSpeed(random, speed, MAX_SPEED[i]);
+                    if (!stillInRace) throw new WipedOutOrSnaggedAFlag();
+                } else {
+                    throw new DisqualifiedException();//we've been dis-qualified
+                }
+
+                if (speed < 7) {
+                    System.out.println("LET'S BE REALISTIC, OK?  LET'S GO BACK AND TRY AGAIN...");
+                    speed = tmpSpeed;
+                    gateCompleted = false;
+                } else {
+                    totalTimeTaken = totalTimeTaken + (MAX_SPEED[i] - speed + 1);
+                    if (speed > MAX_SPEED[i]) {
+                        totalTimeTaken = totalTimeTaken + 0.5f;
+                    }
+                    gateCompleted = true;
+                }
+            }
+
+        }
+        return totalTimeTaken;
+    }
+
+    private static boolean checkAndProcessIfOverMaxSpeed(Random random, int speed, int maxSpeed) {
+        boolean stillInRace = true;
+        if (speed > maxSpeed) {
+            if (random.nextFloat() >= (speed - maxSpeed) * 0.1 + 0.2) {
+                System.out.println("YOU WENT OVER THE MAXIMUM SPEED AND MADE IT!");
+            } else {
+                System.out.print("YOU WENT OVER THE MAXIMUM SPEED AND ");
+                if (random.nextBoolean()) {
+                    System.out.println("WIPED OUT!");
+                } else {
+                    System.out.println("SNAGGED A FLAG!");
+                }
+                stillInRace = false;
+            }
+        } else if (speed > maxSpeed - 1) {
+            System.out.println("CLOSE ONE!");
+        }
+        return stillInRace;
+    }
+
+    private static boolean readRaceAgainChoice(Scanner scan) {
+        System.out.print("\nDO YOU WANT TO RACE AGAIN? ");
+        String raceAgain = "";
+        final String YES = "YES";
+        final String NO = "NO";
+        while (!YES.equals(raceAgain) && !NO.equals(raceAgain)) {
+            raceAgain = scan.nextLine();
+            if (!(YES.equals(raceAgain) || NO.equals(raceAgain))) {
+                System.out.println("PLEASE TYPE 'YES' OR 'NO'");
+            }
+        }
+        return raceAgain.equals(YES);
+    }
+
+    private static void printSpeed(int speed) {
+        System.out.printf("%3d M.P.H.%n", speed);
+    }
+
+    private static void printHowLong(float t, Random random) {
+        System.out.printf("YOU'VE TAKEN %.2f SECONDS.%n", t + random.nextFloat());
+    }
+
+    private static int readOption(Scanner scan) {
+        Integer option = null;
+
+        while (option == null) {
+            System.out.print("OPTION? ");
+            try {
+                option = scan.nextInt();
+            } catch (InputMismatchException ex) {
+                System.out.println("!NUMBER EXPECTED - RETRY INPUT LINE\n");
+            }
+            scan.nextLine();
+            if (option != null && (option > 8 || option < 0)) {
+                System.out.println("WHAT?");
+                option = null;
+            }
+        }
+        return option;
+    }
+
+    private static int readSkierRating(Scanner scan) {
+        int rating = 0;
+
+        while (rating < 1 || rating > 3) {
+            System.out.print("RATE YOURSELF AS A SKIER, (1=WORST, 3=BEST)? ");
+            try {
+                rating = scan.nextInt();
+                if (rating < 1 || rating > 3) {
+                    System.out.println("THE BOUNDS ARE 1-3");
+                }
+            } catch (InputMismatchException ex) {
+                System.out.println("!NUMBER EXPECTED - RETRY INPUT LINE\n");
+            }
+            scan.nextLine();
+        }
+        return rating;
+    }
+
+    private static void printApproxMaxSpeeds(int numGates) {
+        System.out.println("GATE MAX");
+        System.out.println(" #  M.P.H.");
+        System.out.println("---------");
+        for (int i = 0; i < numGates; i++) {
+            System.out.println((i+1) + "  " + MAX_SPEED[i]);
+        }
+    }
+
+    private static void printInstructions() {
+        System.out.println("\n*** SLALOM: THIS IS THE 1976 WINTER OLYMPIC GIANT SLALOM.  YOU ARE");
+        System.out.println("            THE AMERICAN TEAM'S ONLY HOPE OF A GOLD MEDAL.");
+        System.out.println();
+        System.out.println("     0 -- TYPE THIS IS YOU WANT TO SEE HOW LONG YOU'VE TAKEN.");
+        System.out.println("     1 -- TYPE THIS IF YOU WANT TO SPEED UP A LOT.");
+        System.out.println("     2 -- TYPE THIS IF YOU WANT TO SPEED UP A LITTLE.");
+        System.out.println("     3 -- TYPE THIS IF YOU WANT TO SPEED UP A TEENSY.");
+        System.out.println("     4 -- TYPE THIS IF YOU WANT TO KEEP GOING THE SAME SPEED.");
+        System.out.println("     5 -- TYPE THIS IF YOU WANT TO CHECK A TEENSY.");
+        System.out.println("     6 -- TYPE THIS IF YOU WANT TO CHECK A LITTLE.");
+        System.out.println("     7 -- TYPE THIS IF YOU WANT TO CHECK A LOT.");
+        System.out.println("     8 -- TYPE THIS IF YOU WANT TO CHEAT AND TRY TO SKIP A GATE.");
+        System.out.println();
+        System.out.println(" THE PLACE TO USE THESE OPTIONS IS WHEN THE COMPUTER ASKS:");
+        System.out.println();
+        System.out.println("OPTION?");
+        System.out.println();
+        System.out.println("                GOOD LUCK!");
+    }
+
+    private static MenuChoice readMenuOption(Scanner scan) {
+        System.out.print("COMMAND--? ");
+        MenuChoice menuChoice = null;
+
+        while (menuChoice == null) {
+            String choice = scan.next();
+            if (Arrays.stream(MenuChoice.values()).anyMatch(a -> a.name().equals(choice))) {
+                menuChoice = MenuChoice.valueOf(choice);
+            } else {
+                System.out.print("\""+ choice + "\" IS AN ILLEGAL COMMAND--RETRY? ");
+            }
+            scan.nextLine();
+        }
+        return menuChoice;
+    }
+
+    private static void printMenu() {
+        System.out.println("TYPE INS FOR INSTRUCTIONS");
+        System.out.println("TYPE MAX FOR APPROXIMATE MAXIMUM SPEEDS");
+        System.out.println("TYPE RUN FOR THE BEGINNING OF THE RACE");
+    }
+
+    private static int readNumberOfGatesChoice(Scanner scan) {
+        int numGates = 0;
+        while (numGates < 1) {
+            System.out.print("HOW MANY GATES DOES THIS COURSE HAVE (1 TO 25)? ");
+            numGates = scan.nextInt();
+            if (numGates > MAX_NUM_GATES) {
+                System.out.println(MAX_NUM_GATES + " IS THE LIMIT.");
+                numGates = MAX_NUM_GATES;
+            }
+        }
+        return numGates;
+    }
+
+    private static void printIntro() {
+        System.out.println("                                SLALOM");
+        System.out.println("              CREATIVE COMPUTING  MORRISTOWN, NEW JERSEY");
+        System.out.println("\n\n");
+    }
+
+    private enum MenuChoice {
+        INS, MAX, RUN
+    }
+
+    private static class DisqualifiedException extends Exception {
+    }
+
+    private static class WipedOutOrSnaggedAFlag extends Exception {
+    }
+
+    private static class Medals {
+        private int gold = 0;
+        private int silver = 0;
+        private int bronze = 0;
+
+        public Medals(int gold, int silver, int bronze) {
+            this.gold = gold;
+            this.silver = silver;
+            this.bronze = bronze;
+        }
+
+        public int getGold() {
+            return gold;
+        }
+
+        public int getSilver() {
+            return silver;
+        }
+
+        public int getBronze() {
+            return bronze;
+        }
+    }
+
+
+}