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  1. #51
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    Re: Sdd 2017 hsc

    Selection doesn't work, though?
    Selection starts with the first element in the array, and then finds the max/min element and swaps the two. Insertion and bubble can work fine, selection can never.

    If we were to get something like this:
    1 2 3 4 6 5

    Selection takes the value inside the first element: 1
    It then finds the maximum, which is 6, and swaps them.
    6 2 3 4 1 5

    The smallest/largest value will always become the first element in the unsorted array, which means that it doesn't work with just the last two elements in an array on the first pass.
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    Re: Sdd 2017 hsc

    Oh damn, I thought that selection could've started with the last element, whoops

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    Re: Sdd 2017 hsc

    Quote Originally Posted by jarrjam View Post
    Wasn't the question asking 'which sort COULD have been used', which would imply that if its possible to affect only the last 2 elements with that sort then its correct (maybe I remembered the question wrong though)? I said bubble and selection. At the time, I thought if it was insertion, on the first pass it would have checked the 2nd element and if it did need to move the 2nd element to the end of the array, it would have changed the values of not only the last two elements but also the 2nd element. Bubble could also work because it might only swap the last 2 values on the first pass.
    Hmmm, could of been, if it was that yeah all three would be correct. Though I thought it said only affect the the last 2.


    Quote Originally Posted by jarrjam View Post
    Alright, thanks for clarifying. I must've remembered the answers wrong. I'm pretty sure I chose one of the answers where it said that for sequential "User input does not drastically change the execution". Does anyone happen to remember the options for event driven?
    I remember narrowing it down to A and B (I think), can't remember the exact options, hopefully they put the paper up soon.

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    Re: Sdd 2017 hsc

    I've seen selection sorts where they swap the min/max value element with the last element in the array. The 2016 HSC Software Paper had Q13 which had the answer as a selection sort which swapped the max value element with the last element in the array.

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    Re: Sdd 2017 hsc

    Quote Originally Posted by sparcut View Post
    Hmmm, could of been, if it was that yeah all three would be correct. Though I thought it said only affect the the last 2.




    I remember narrowing it down to A and B (I think), can't remember the exact options, hopefully they put the paper up soon.

    A and B were definitely incorrect, as they said the event driven approach occurred in a fixed sequence of processes, which is definitely incorrect.
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    Re: Sdd 2017 hsc

    Yeah I thought it would not have been bubble as it usually takes more than one pass for bubble unless you start at the end, which I haven't really seen

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    Re: Sdd 2017 hsc

    Quote Originally Posted by lilrose View Post
    Oh damn, I thought that selection could've started with the last element, whoops
    Quote Originally Posted by Sxerks3 View Post
    Selection doesn't work, though?
    Selection starts with the first element in the array, and then finds the max/min element and swaps the two. Insertion and bubble can work fine, selection can never.

    If we were to get something like this:
    1 2 3 4 6 5

    Selection takes the value inside the first element: 1
    It then finds the maximum, which is 6, and swaps them.
    6 2 3 4 1 5

    The smallest/largest value will always become the first element in the unsorted array, which means that it doesn't work with just the last two elements in an array on the first pass.
    Selection can start with the last element. It doesn't have to start with the first, it can be flipped either way since it will result in the same answer in the end.

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    Re: Sdd 2017 hsc

    Did a quick search on selection sort, and all of the articles I've read state that the min/max value is swapped with the value at the leftmost of the unsorted section (ie first element of the unsorted).

    well, shit sadlyfe: http://ee.hawaii.edu/~tep/EE160/Book...on2.1.2.1.html
    Last edited by Sxerks3; 1 Nov 2017 at 3:38 PM.
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    Re: Sdd 2017 hsc

    Quote Originally Posted by Sxerks3 View Post
    Did a quick search on selection sort, and all of the articles I've read state that the min/max value is swapped with the value at the leftmost of the unsorted section (ie first element of the unsorted).

    well, shit sadlyfe: http://ee.hawaii.edu/~tep/EE160/Book...on2.1.2.1.html
    Mmm, it really doesn't matter which way you go, just need to find the next largest/smallest and move it to the "sorted" section of the array. Only advantage of moving from the right to left would be that decrementing loops are marginally faster than incrementing loops - even so, now I think of it you could still start from the right decremented and have the sorted part on the left.

    Ehh, it'll be interesting to see the answer to this question.

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    Re: Sdd 2017 hsc

    For the Boolean values in a one-dimensional array I did teams winning/ losing (although drawing is an option) because different Sets of traffic lights implies a two-dimensional array and the fact that most lights are Red, yellow or green. Could of been either though.

    As for the sort our software teacher told us it can start from the left or the right so I based it off that. Therefore I got D (i.e. all off the sorts)

    1 2 3 5 4

    Bubble sort in this case would bubble 5 past 4 on first pass (changing last 2 values)

    If insertion sort starts from right it will output same result as bubble sort on first pass

    Finally, if selection sort also starts from the right it will swap 5 and 4 (selecting 5 as the highest) also changing last 2 values in same way as others above.

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    Re: Sdd 2017 hsc

    Quote Originally Posted by lilrose View Post
    What did everyone get for the MC sort one? I chose selection and insert though i was tempted to go with all three
    It was asking if it will affect the last certain number of elements after a certain number of passes right?

    I avoided insertion sort because it goes sort of like this:
    126589443
    1|26589443
    12|6589443
    126|589443
    1256|89443
    and so on, does it not?
    Like it takes the next number and inserts it so it doesn't reach the last two elements until it has almost finished inserting?
    Meanwhile selection selects either the lowest or highest and places it at the front.
    E.g. 24567831 It takes 1 and puts it at front: 12|456783
    and bubble definitely can affect last two elements as it bubbles numbers to the end.

    So I went for selection and bubble for that MC. I'm pretty sure that's right unless i misread the question in the exam.
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    Re: Sdd 2017 hsc

    Quote Originally Posted by silverdawn565 View Post
    It was asking if it will affect the last certain number of elements after a certain number of passes right?

    I avoided insertion sort because it goes sort of like this:
    126589443
    1|26589443
    12|6589443
    126|589443
    1256|89443
    and so on, does it not?
    Like it takes the next number and inserts it so it doesn't reach the last two elements until it has almost finished inserting?
    Meanwhile selection selects either the lowest or highest and places it at the front.
    E.g. 24567831 It takes 1 and puts it at front: 12|456783
    and bubble definitely can affect last two elements as it bubbles numbers to the end.

    So I went for selection and bubble for that MC. I'm pretty sure that's right unless i misread the question in the exam.
    I'm totally completely sure that multi was D. I have a teacher who practically wrote the original SDD syllabus, and she said it was D when we spoke after the exam - D as in all sorts work

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    Re: Sdd 2017 hsc

    Quote Originally Posted by jarrjam View Post
    Wasn't the question asking 'which sort COULD have been used', which would imply that if its possible to affect only the last 2 elements with that sort then its correct (maybe I remembered the question wrong though)? I said bubble and selection. At the time, I thought if it was insertion, on the first pass it would have checked the 2nd element and if it did need to move the 2nd element to the end of the array, it would have changed the values of not only the last two elements but also the 2nd element. Bubble could also work because it might only swap the last 2 values on the first pass.
    Sorry, missed your response. But I basically just repeated what you said.
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    Re: Sdd 2017 hsc

    Quote Originally Posted by skelmo View Post
    I'm totally completely sure that multi was D. I have a teacher who practically wrote the original SDD syllabus, and she said it was D when we spoke after the exam - D as in all sorts work
    Really? Well I'm lost on that... maybe the insertion sort starts from the last two elements?
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    Re: Sdd 2017 hsc

    Just a bit curious, are any of you guys in this form James Ruse Yr 10 accelerants? I just have a gut feeling, lol. Because I heard that they do year 12 HSC SDD in year 10

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    Re: Sdd 2017 hsc

    Quote Originally Posted by silverdawn565 View Post
    Really? Well I'm lost on that... maybe the insertion sort starts from the last two elements?
    its about the wording - it didn't say ALWAYS - it said CAN.
    It is very possible to give a specific insertion sort example in which the criteria they gave can occur!
    Although, I can't remember the question exactly, I would happily give an example.
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    Re: Sdd 2017 hsc

    Quote Originally Posted by skelmo View Post
    its about the wording - it didn't say ALWAYS - it said CAN.
    It is very possible to give a specific insertion sort example in which the criteria they gave can occur!
    Although, I can't remember the question exactly, I would happily give an example.
    I guess that makes sense. I knew selection sorts could swap with the last element instead of the first element because I had seen it in a past paper but idk why I didn't think the same way for insertion sorts.

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    Re: Sdd 2017 hsc

    Quote Originally Posted by skelmo View Post
    I'm totally completely sure that multi was D. I have a teacher who practically wrote the original SDD syllabus, and she said it was D when we spoke after the exam - D as in all sorts work
    damn I changed my answer last minute

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    Re: Sdd 2017 hsc

    Same, my instinct was all, but like I then thought selection couldn't. ((
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    Re: Sdd 2017 hsc

    What did you guys choose for MC 6? I said C.
    Also I was stuck on A or B for MC 8. I went with B but the answer might've been A...
    Also was unsure about 10.
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    Re: Sdd 2017 hsc

    Quote Originally Posted by silverdawn565 View Post
    What did you guys choose for MC 6? I said C.
    Also I was stuck on A or B for MC 8. I went with B but the answer might've been A...
    Also was unsure about 10.
    MC 6 was either C or D.
    MC 8 is A.
    MC 10 was either C or B.
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    Re: Sdd 2017 hsc

    Thanks!
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    Re: Sdd 2017 hsc

    Quote Originally Posted by Sxerks3 View Post
    A and B were definitely incorrect, as they said the event driven approach occurred in a fixed sequence of processes, which is definitely incorrect.
    Yeah, was flipping through the paper since it's up, almost threw my mouse across the room when I saw the question again, I can't believe I made such a stupid mistake.

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    Re: Sdd 2017 hsc

    Quote Originally Posted by skelmo View Post
    its about the wording - it didn't say ALWAYS - it said CAN.
    It is very possible to give a specific insertion sort example in which the criteria they gave can occur!
    Although, I can't remember the question exactly, I would happily give an example.
    Mmmm, the question uses "only" and "ALL" as in:

    After the first pass of a sort, only the last two elements of an array have changed value.
    Which list identifies ALL the possible sort methods that could have been used?

    A. Bubble, selection
    B. Bubble, insertion
    C. Insertion, selection
    D. Bubble, selection, insertion

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