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    <p>This doesn't look like a homework problem. Were it a homework problem, the author would have written about seven to ten lines of code, with a proof of effectiveness, and turned it in. This guy is trying to be fancy, and it's biting him in the backside. You can tell by the way he drops to insertion-sort for so-called "small" intervals. (Clue: the threshold interval size is more than half the test data size. Give your algorithm some room to recurse if you want to test it well.) Second, there is the extra work he's doing to find an ideal pivot. This kind of complexity comes at a cost.</p> <p>This is a hobbyist at work. What he needs is not just an answer. He needs an approach to solving hard problems. Quicksort is just the vehicle for that education.</p> <p>Here's my approach.</p> <p>The trick is to write Quicksort as Quicksort, get it working, and then worry about fancy special tricks. Kill off the noise about insertion sorting small intervals. Just assume that any interval of size zero or one is already sorted (which is your base case) and then work on making your partitioning code work using the left end of the interval as the pivot (as in classical original Quicksort), and you might consider printing the results of your data after one partitioning pass as a way to show yourself that it works. You'll develop testing skills that way. Anyway, once you have a working quicksort, then you can do things like separate pivot selection into a function and play with the implementation.</p> <p>Good luck, and enjoy your project. Don't forget, though: We want timings, and especially time comparisons with the sort routine in the standard library!</p>
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    1. POQuicksort not working
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    1. COAll of that is in the assignment. For testing I was printing the pivot, the array after findPivot goes over the array, every swap that was made (that was a lot to go through) and then a comparison of the arrays before and after partitioning.
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    2. COAn assignment, then. Well, others have pointed out some specific bugs. One pattern of bug I see is a confusion of the integers which represent indexes into the array with the integers which represent the data to be sorted. So, for example, try renaming "pivot" to "pivot_index" and "pivot_value" in your code, and then you'll see most of the problems jump out at you. The same is true of your "start" and "end". Now, if instead you passed "start" and "interval size" then some of the math might be easier...
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    3. COAs it happens, it looks like the only flaw probably is in find_pivot looking outside the range.
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