CSE143X Key to Sample Final, Autumn 2018 handout #24 1. Preorder traversal 4, 2, 7, 9, 3, 6, 1, 8, 5, 0 Inorder traversal 7, 9, 2, 3, 6, 4, 8, 1, 0, 5 Postorder traversal 9, 7, 6, 3, 2, 8, 0, 5, 1, 4 2. One possible solution appears below. public void writeSquares(int n) { if (n < 1) { throw new IllegalArgumentException(); } if (n == 1) { System.out.print(1); } else if (n % 2 == 1) { System.out.print(n * n + ", "); writeSquares(n - 1); } else { writeSquares(n - 1); System.out.print(", " + n * n); } } 3. Statement Output ------------------------------------------------------------ var1.method1(); compiler error var2.method1(); Rain 1 var1.method2(); Sleet 2/Snow 2/Sleet 3 var2.method2(); Rain 2 var3.method2(); Sleet 2/Snow 2/Fog 3 var4.method2(); compiler error var5.method2(); Sleet 2/Snow 2/Fog 3 var1.method3(); Sleet 3 var2.method3(); Snow 3 var3.method3(); Fog 3 var4.method3(); compiler error var5.method3(); Fog 3 ((Rain)var4).method1(); runtime error ((Fog)var5).method1(); Fog 1 ((Sleet)var3).method1(); compiler error ((Sleet)var3).method3(); Fog 3 ((Fog)var6).method3(); runtime error ((Snow)var4).method2(); Snow 2 ((Sleet)var4).method3(); runtime error ((Rain)var6).method3(); Snow 3 4. Two possible solutions appear below. public Set<Point> extractEqual(Set<Point> data) { Set<Point> result = new HashSet<Point>(); for (Point p : data) { if (p.getX() == p.getY()) { result.add(p); } } return result; } public Set<Point> extractEqual(Set<Point> data) { Set<Point> result = new HashSet<Point>(); Iterator<Point> i = data.iterator(); while (i.hasNext()) { Point p = i.next(); if (p.getX() == p.getY()) { result.add(p); } } return result; } 5. One possible solution appears below. public static int parityMatches(Stack<Integer> s1, Stack<Integer> s2) { if (s1.size() != s2.size()) { throw new IllegalArgumentException(); } Queue<Integer> q = new LinkedList<Integer>(); int count = 0; while (!s1.isEmpty()) { int num1 = s1.pop(); int num2 = s2.pop(); if (num1 % 2 == num2 % 2) { count++; } q.add(num1); q.add(num2); } while (!q.isEmpty()) { s1.push(q.remove()); } while (!s1.isEmpty()) { q.add(s1.pop()); } while (!q.isEmpty()) { s2.push(q.remove()); s1.push(q.remove()); } return count; } 6. One possible solution appears below. public int purebredOdds() { return purebredOdds(overallRoot); } private int purebredOdds(IntTreeNode root) { if (root == null || root.data % 2 == 0) { return 0; } else { return 1 + purebredOdds(root.left) + purebredOdds(root.right); } } 7. One possible solution appears below. public Map<String, List<Integer>> indexMap(List<String> data) { Map<String, List<Integer>> result = new TreeMap<String, List<Integer>>(); for (int i = 0; i < data.size(); i++) { String next = data.get(i); if (!result.containsKey(next)) { result.put(next, new ArrayList<Integer>()); } result.get(next).add(i); } return result; } 8. One possible solution appears below. class BookData implements Comparable<BookData> { private String title; private int reviews; private double total; public BookData(String title) { this.title = title; this.reviews = 0; this.total = 0.0; } public void review(double rating) { reviews++; total += rating; } public double getRating() { return total / reviews; } public String toString() { return title + " " + getRating() + " (reviews: " + reviews + ")"; } public int compareTo(BookData other) { if (getRating() > other.getRating()) { return -1; } else if (getRating() < other.getRating()) { return 1; } else { return other.reviews - reviews; } } } 9. One possible solution appears below. public void stretch() { overallRoot = stretch(overallRoot); } private IntTreeNode stretch(IntTreeNode root) { if (root != null) { root.left = stretch(root.left); root.right = stretch(root.right); if (root.left != null && root.right == null) { root = new IntTreeNode(1, root, null); } else if (root.left == null && root.right != null) { root = new IntTreeNode(1, null, root); } } return root; } 10. One possible solution appears below. public void mergeFrom(LinkedIntList other) { if (other.front != null) { if (front == null) { front = other.front; } else { ListNode current1 = front; ListNode current2 = other.front; if (front.data <= other.front.data) { current1 = current1.next; } else { front = other.front; current2 = current2.next; } ListNode current3 = front; while (current1 != null && current2 != null) { if (current1.data <= current2.data) { current3.next = current1; current1 = current1.next; } else { current3.next = current2; current2 = current2.next; } current3 = current3.next; } if (current1 != null) { current3.next = current1; } else { current3.next = current2; } } other.front = null; } }
Stuart Reges
Last modified: Mon Dec 3 13:49:14 PST 2018