check-in-meeting-answers.md

CSE 143

Check-in Meeting Answers

Week 4

1. One possible answer is shown below.

   public static String collapseSequence(String str, char ch) {
   	if (str.length() < 2) {
   		return str;
   	}
   	else {
   		if (str.charAt(0) == ch && str.charAt(1) == ch) {
   			return collapseSequence(str.substring(1), ch);
   		} else {
   			return str.charAt(0) + collapseSequence(str.substring(1), ch);
   		}
   		
   	}
   }

2. Possible answers are shown in the table below.

           before                   after                      code
   -----------------------+-----------------------+-------------------------------
                          |                       |
                          |                       |	q = p.next.next;
    p->[1]->[2]->[3]      | p->[1]->[2]           |	p.next.next = null;
                          |                       |
                          |                       |
    q                     | q->[3]                |
                          |                       |
   -----------------------+-----------------------+-------------------------------
                          |                       |
                          |                       |	q.next = p.next;
    p->[1]->[3]           | p->[1]->[2]->[3]      |	p.next = q;
                          |                       |	q = null;
                          |                       |
    q->[2]                | q                     |
                          |                       |
   -----------------------+-----------------------+-------------------------------
                          |                       |
                          |                       |	p.next.next = q.next;
    p->[1]->[2]           | p->[2]->[4]           |	q.next = p;
                          |                       |	p = p.next;
                          |                       |	q.next.next = null;
    q->[3]->[4]           | q->[3]->[1]           |
                          |                       |
                          |                       |
                          |                       |
                          |                       |
   -----------------------+-----------------------+-------------------------------
                          |                       |
                          |                       |	ListNode temp = p.next.next;
    p->[1]->[2]->[3]      | p->[2]->[1]->[4]      |	temp.next = q.next;
                          |                       |	p.next.next = p;
                          |                       |	p = p.next;
    q->[4]->[5]           | q->[3]->[5]           |	q.next = null;
                          |                       |	p.next.next = q;
                          |                       |	q = temp;
                          |                       |
                          |                       |
                          |                       |
                          |                       |
                          |                       |
   -----------------------+-----------------------+-------------------------------