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Key to CSE143 Sample Midterm, Spring 2024 handout #13
1. Method Call Output Produced
------------------------------------------------
mystery(9) **=9
mystery(42) *2*4*=
mystery(703) *3*0**=7
mystery(5821) *1*2***=58
mystery(83105) **0*1*3**=85
2. One possible solution appears below.
public int countDigit(int digit, int number) {
if (number < 0 || digit < 0 || digit >= 10) {
throw new IllegalArgumentException();
}
if (number < 10) {
if (number == digit) {
return 1;
} else {
return 0;
}
} else if (number % 10 == digit) {
return 1 + countDigit(digit, number / 10);
} else {
return countDigit(digit, number / 10);
}
}
3. Statement Output
------------------------------------------------------------
var1.method1(); Wall 1
var2.method1(); Dragon 1/Raven 1
var3.method1(); Raven 1
var4.method1(); compiler error
var5.method1(); Wall 1
var6.method1(); compiler error
var1.method2(); Raven 2/Wall 1
var2.method2(); Raven 2/Dragon 1/Raven 1
var3.method2(); Raven 2/Raven 1
var4.method2(); compiler error
var5.method2(); Raven 2/Wall 1
var6.method2(); compiler error
((Dragon)var1).method3(); compiler error
((Hand)var6).method3(); Hand 3
((Wall)var4).method1(); runtime error
((Raven)var6).method2(); Raven 2/Raven 1
((Raven)var4).method1(); Dragon 1/Raven 1
((Wall)var6).method3(); runtime error
((Wall)var3).method3(); runtime error
((Wall)var5).method3(); Wall 3
4. before after code
-----------------------+-----------------------+-------------------------------
p->[1] | p | q.next.next = p;
| | p = null;
q->[2]->[3] | q->[2]->[3]->[1] |
-----------------------+-----------------------+-------------------------------
p->[1]->[2]->[3] | p->[2]->[3] | q = p;
| | p = p.next;
q | q->[1] | q.next = null;
-----------------------+-----------------------+-------------------------------
p->[1]->[2] | p->[2] | q.next.next = q;
| | q = q.next;
q->[3]->[4] | q->[4]->[3]->[1] | q.next.next = p;
| | p = p.next;
| | q.next.next.next = null;
-----------------------+-----------------------+-------------------------------
p->[1]->[2] | p->[4]->[2]->[3] | q.next.next.next = p;
| | ListNode temp = q;
q->[3]->[4]->[5] | q->[5]->[1] | q = q.next.next;
| | temp.next.next = q.next.next;
| | p.next.next = temp;
| | p = temp.next;
| | p.next.next.next = null;
| | q.next.next = null;
-----------------------+-----------------------+-------------------------------
5. One possible solution appears below.
public void removeLast(int n) {
int index = -1;
for (int i = 0; i < size; i++) {
if (elementData[i] == n) {
index = i;
}
}
if (index != -1) {
for (int j = index; j < size - 1; j++) {
elementData[j] = elementData[j + 1];
}
size--;
}
}
6. One possible solution appears below.
public void splitStack(Stack<Integer> s) {
Queue<Integer> q = new LinkedList<>();
while (!s.isEmpty()) {
q.add(s.pop());
}
int oldSize = q.size();
for (int i = 0; i < oldSize; i++) {
int n = q.remove();
if (n % 2 == 0) {
q.add(n);
} else {
s.push(n);
}
}
while (!q.isEmpty()) {
s.push(q.remove());
}
while (!s.isEmpty()) {
q.add(s.pop());
}
while (!q.isEmpty()) {
s.push(q.remove());
}
}
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