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  4. Quicksort slower than mergesort...

Quicksort slower than mergesort...

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  • G Offline
    G Offline
    gautgaut
    wrote on last edited by
    #1

    I try to implement classical sorting algorithm, I do not understand why my quicksort is slower than my mergesort. I spend a lot of time trying to understand why. Do you have any idea ? For both :

    #define ARRAY_INDEX(tab, i) ((void*)((char*)(tab) + (i) * type_size))

    My mergesort :

    void merge(void *tab, void *aux, int a, int b)
    {
    int i, j, k, mid;

    ft\_copy\_tab(tab, aux, a, b);
    mid = (a + b) / 2;
    i = a;
    j = mid + 1;
    k = a;
    while (k <= b)
    {
    	if (i > mid)
    		ft\_copy\_index(tab, aux, k, j++);
    	else if (j > b)
    		ft\_copy\_index(tab, aux, k, i++);
    	else if (f\_cmp(ARRAY\_INDEX(aux, i), ARRAY\_INDEX(aux, j)) > 0)
    		ft\_copy\_index(tab, aux, k, j++);
    	else
    		ft\_copy\_index(tab, aux, k, i++);
    	k++;
    }
    return ;
    

    }

    My quicksort :

    void ft_quicksort(void *tab, int a, int b)
    {
    int i, lower, upper;

    if (a >= b)
    	return ;
    lower = a;
    upper = b;
    i = a;
    while (i <= upper)
    {
    	if (f\_cmp(ARRAY\_INDEX(tab, lower), ARRAY\_INDEX(tab, i)) > 0)
    	{
    		ft\_swap(tab, lower, i, type\_size);
    		lower++;
    		i++;
    	}
    	else if (f\_cmp(ARRAY\_INDEX(tab, lower), ARRAY\_INDEX(tab, i)) < 0)
    	{
    		ft\_swap(tab, i, upper, type\_size);
    		upper--;
    	}
    	else
    		++i;
    }
    ft\_sort(tab, a, lower - 1);
    ft\_sort(tab, upper + 1, b);
    

    }

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