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Key to CSE143 Midterm, Spring 2012 handout #23
1. Method Call Output Produced
------------------------------------------------
mystery(1); 1
mystery(2); 2, 1
mystery(4); 4, 2, 1
mystery(8); 8, 4, 2, 1
mystery(10); 10, 5, 16, 8, 4, 2, 1
2. One possible solution appears below.
public void printDashed(int n) {
if (n < 0) {
System.out.print("-");
printDashed(-n);
} else if (n < 10) {
System.out.print(n);
} else {
printDashed(n / 10);
System.out.print("-" + n % 10);
}
}
3. One possible solution appears below.
public int removeLast() {
if (front == null) {
throw new NoSuchElementException();
} else if (front.next == null) {
int result = front.data;
front = null;
return result;
} else {
ListNode current = front;
while (current.next.next != null) {
current = current.next;
}
int result = current.next.data;
current.next = null;
return result;
}
}
4. Statement Output
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var1.method1(); Peak 1/Cliff 3/Peak 3
var2.method1(); Peak 1/Gorge 3
var3.method1(); Peak 1/Hill 3
var4.method1(); Peak 1/Gorge 3
var5.method1(); Peak 1/Peak 3
var6.method1(); compiler error
var1.method2(); compiler error
var2.method2(); Gorge 2
var3.method2(); compiler error
var1.method3(); Cliff 3/Peak 3
var2.method3(); Gorge 3
var3.method3(); Hill 3
((Gorge)var6).method1(); runtime error
((Cliff)var3).method2(); compiler error
((Gorge)var4).method2(); Gorge 2
((Gorge)var3).method2(); runtime error
((Hill)var3).method2(); Hill 2
((Gorge)var1).method1(); runtime error
((Cliff)var4).method3(); Gorge 3
((Peak)var6).method3(); Cliff 3/Peak 3
5. One possible solution appears below.
public int removeMin(Stack<Integer> s) {
Queue<Integer> q = new LinkedList<Integer>();
int min = s.pop();
q.add(min);
while (!s.isEmpty()) {
int next = s.pop();
if (next < min)
min = next;
q.add(next);
}
while (!q.isEmpty()) {
int next = q.remove();
if (next != min)
s.push(next);
}
while (!s.isEmpty())
q.add(s.pop());
while (!q.isEmpty())
s.push(q.remove());
return min;
}
6. One possible solution appears below.
public void mirror() {
int last = 2 * size - 1;
for (int i = 0; i < size; i++) {
elementData[last - i] = elementData[i];
}
size = size * 2;
}
]]>
Stuart Reges
Last modified: Fri Sep 16 16:16:07 PDT 2011