Hi: I looked it up in google because I couldn't remember how quicksort worked. ( i'm getting old ).
the java code is below. I didn't translate it but what you are doing incorrectly is calling partition recursively when you need to call the quicksort algorithm recursively. you'll see what I mean if you look at the java code below. there are many links on the internet that explains why it works with examples etc. here's one: http://www.algolist.net/Algorithms/Sorting/Quicksort good luck. #============================================================== int partition(int arr[], int left, int right) { int i = left, j = right; int tmp; int pivot = arr[(left + right) / 2]; while (i <= j) { while (arr[i] < pivot) i++; while (arr[j] > pivot) j--; if (i <= j) { tmp = arr[i]; arr[i] = arr[j]; arr[j] = tmp; i++; j--; } }; return i; } #=============================================================== void quickSort(int arr[], int left, int right) { int index = partition(arr, left, right); if (left < index - 1) quickSort(arr, left, index - 1); if (index < right) quickSort(arr, index, right); } On Sat, Sep 3, 2011 at 10:50 PM, Jim Holtman <jholt...@gmail.com> wrote: > have you tried to debug it yourself. All you said is that 'it went wrong'. > that is not a very clear statement of the problem. If I were to start > looking at it, I would put some print statements in it to see what is > happening on eachpath and with each set of data. Have you tried this? > > Sent from my iPad > > On Sep 3, 2011, at 21:51, warc <conny-cla...@gmx.de> wrote: > >> Hey guys, >> I tried to program quicksort like this but somethings wrong. >> >> please help >> >> >> >>> partition <- function(x, links, rechts){ >>> >>> i <- links >>> j <- rechts >>> t <- 0 >>> pivot <- sample(x[i:j],1) >>> >>> while(i <= j){ >>> >>> while(x[i] <= pivot){ >>> i = i+1} >>> >>> while(x[j] >= pivot){ >>> j = j-1} >>> >>> if( i <= j){ >>> >>> t = x[i] >>> x[i] = x[j] >>> x[j] = t >>> >>> i=i+1 >>> j=j-1 >>> >>> } >>> print(pivot) >>> >>> >>> } >>> #Rekursion >>> >>> if(links < j){ >>> partition(x, links, j)} >>> if(i < rechts){ >>> partition(x, i, rechts)} >>> >>> return(x) >>> } >>> >>> >>> quicksort <- function(x){ >>> >>> >>> >>> partition(x, 1, length(x)) >>> } >> >> >> >> thx >> >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/what-is-wrong-with-my-quicksort-tp3788681p3788681.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
