CODEWITHSUNDEEP
cquicksort
user2751812
user2751812

Reputation: 13

implementing quicksort in c

void qkSort (int *arr,int size)
{
    if (size>1)
    {
        int p = partition(arr,size);
    qkSort(arr,p);
    qkSort(arr+p+1,size-(p-1));
    }
    return;
}

int partition(int *arr,int size)
{
    int i,j,pivot,temp;
    pivot = size-1;
    for(i=0,j=-1;i<size-1;++i)
    {   
        if (arr[i]<arr[pivot])
        {
             ++j;
             if(i!=j)
             {
                 temp = arr[i];
                 arr[i] = arr[j];
                 arr[j] = temp;
             }
        }
    }

    temp = arr[pivot];
    arr[pivot] = arr[j+1];
    arr[j+1] = temp;

    pivot = j+1;

    return pivot;
}

The program hangs up. Monitoring the variables by gdb shows that the second recursive call doesnt get its argument passed correctly. Please help! Thank you in advance!

Upvotes: 0

Views: 825

Answers (2)

Khalid Waseem
Khalid Waseem

Reputation: 49

Your calculation of the size of 2nd array is wrong.

qkSort(arr+p+1,size-(p-1));

This will work. 

qkSort(arr+p+1,(size-p)-1);

Upvotes: 0

bblincoe
bblincoe

Reputation: 2483

Please refer to: http://p2p.wrox.com/visual-c/66347-quick-sort-c-code.html

This example should help you get started.

Upvotes: 2

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