Key to CSE142 Final, Spring 2012 1. Original List Final list ----------------------------------------------- {1, 0, 4, 2} {10, 6, 4, 2} {17, 12, 8, 1, 4} {11, 6, 5, 1, 4} {23, 5, 14, 6, 2} {22, 14, 8, 6, 2} {17, 19, 7, 4, 1, 1} {8, 5, 3, 2, 1, 1} 2. Reference Mystery. The program produces the following output: [w:20 h:40] 2 40 [w:20 h:40] 2 10 [w:60 h:10] 3 10 [w:60 h:10] 2 3 3. Inheritance Mystery. The program produces the following output: Diamond Ruby 1 Emerald 2 Emerald Ruby 1 Emerald 2 Emerald Emerald 1 Emerald 2 Garnet Garnet 1 Emerald 2 4. Token-based processing public static double lowestPrice(Scanner s) { String name = s.next(); double price = s.nextDouble(); double lowest = price; while(s.hasNext()) { String sign = s.next(); double amt = s.nextDouble(); if (sign.equals("+")) { price += amt; } else { price -= amt; } if (price < lowest) { lowest = price; } } System.out.println("Lowest " + name + " price today: \$" + lowest); return lowest; } 5. Line-based processing public static boolean hasAlternatingParity(Scanner s) { String l1 = ""; if (s.hasNextLine()) { l1 = s.nextLine(); } while (s.hasNextLine()) { String l2 = s.nextLine(); if (l1.length() % 2 == l2.length() % 2) { return false; } l1 = l2; } return true; } public static boolean hasAlternatingParity(Scanner s) { int parity = 0; if (s.hasNextLine()) { String line = s.nextLine(); parity = line.length() % 2; } while (s.hasNextLine()) { String line = s.nextLine(); if (line.length() % 2 == parity) { return false; } parity = line.length() % 2; } return true; } 6. Array programming public static int[] insertMiddle(int[] a, int[] b) { int[] result = new int[a.length + b.length]; for (int i = 0; i < a.length / 2; i++) { result[i] = a[i]; } for (int i = 0; i < b.length; i++) { result[i + a.length / 2] = b[i]; } for (int i = a.length / 2; i < a.length; i++) { result [i + b.length] = a[i]; } /* Also okay: * * for (int i = 0; i < a.length / 2 + (a.length % 2); i++) * result[i + ((a.length / 2) + b.length)] = a[i + (a.length / 2)]; */ return result; } public static int[] insertMiddle(int[] a, int[] b) { int lengthA = a.length; int lengthB = b.length; int[] result = new int[lengthA + lengthB]; for (int i = 0; i < result.length; i++) { if (i < lengthA / 2) result[i] = a[i]; else if (i < (lengthA / 2 + lengthB)) result[i] = b[i - lengthA / 2]; else result[i] = a[i - lengthB]; } return result; } public static int[] insertMiddle(int[] a, int[] b) { int[] c = new int[a.length + b.length]; int n = 0; for (int i = 0; i < a.length / 2; i++) { c[n] = a[i]; n++; } for (int i = 0; i < b.length; i++) { c[n] = b[i]; n++; } for (int i = a.length / 2; i < a.length; i++) { c[n] = a[i]; n++; } return c; } 7. Critters public class JellyFish extends Critter { private int drift; private int moveCount; private int driftCount; private String display; public JellyFish() { Random r = new Random(); drift = r.nextInt(9) + 1; display = "D"; } public int getDrift() { return drift; } public boolean eat() { driftCount = drift; display = "D"; return true; } public Direction getMove() { if (driftCount != 0) { driftCount--; return Direction.WEST; } Direction result; if (moveCount % 3 == 0) { result = Direction.NORTH; display = "D"; } else { result = Direction.CENTER; display = "o"; } moveCount++; return result; } public String toString() { return display; } } 8. Array programming public static void limitRuns(int[] nums, int n) { int count = 1; for (int i = nums.length - 1; i > 0; i--) { if (nums[i] == nums[i - 1]) { count++; if (count > n) { for (int j = i; j < nums.length - 1; j++) { nums[j] = nums[j + 1]; } nums[nums.length - 1] = 0; } } else { count = 1; } } } public static void limitRuns(int[] nums, int n) { int tot = 0; int count = 1; for (int i = 1; i < nums.length; i++) { if (nums[i] == nums[i - 1]) { count++; } else { if (count > n) { int amt = count - n; tot += amt; for (int j = i; j < nums.length; j++) { nums[j - amt] = nums[j]; } i -= amt; // IMPORTANT } count = 1; } } for (int i = nums.length - tot; i < nums.length; i++) { nums[i] = 0; } } // need to be careful not to be stuck in infinite loop with 0s at end! public static void limitRuns(int[] nums, int n) { int count = 1; int tot = 1; for (int i = 1; i < nums.length - tot; i++) { if (nums[i] == nums[i - 1]) { count++; if (count > n) { for (int j = i; j < nums.length - tot; j++) { nums[j] = nums[j + 1]; } nums[nums.length - tot] = 0; tot++; i--; } } else { count = 1; } } } public static void limitRuns(int[] nums, int n) { int nonReps = 1; int count = 1; for (int i = 1; i < nums.length; i++) { if (nums[i] == nums[i - 1]) { count++; } if (nums[i] != nums[i - 1]) { count = 1; } if (nums[i] != nums[i - 1] || count <= n) { nums[nonReps] = nums[i]; nonReps++; } } for (int i = nonReps; i < nums.length; i++) { nums[i] = 0; } }