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107-quick_sort_hoare.c
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107-quick_sort_hoare.c
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#include "sort.h"
void swap(int *x, int *y);
/**
* quick_sort_hoare - base of quicksort_fn_hoare
*
* @array: array of numbers
* @size: siz of th array
*
* Return: void
*/
void quick_sort_hoare(int *array, size_t size)
{
if (array == NULL || size < 2)
return;
quicksort_fn_hoare(array, 0, size - 1, size);
}
/**
* quicksort_fn_hoare - quick sort algorithm
*
* @A: array of numbers
* @size: siz of th array
* @low: the first index
* @high: the last index
*
* Return: void
*/
void quicksort_fn_hoare(int A[], int low, int high, size_t size)
{
int partitionIndex;
if (high > low)
{
partitionIndex = hoare_rt_pvt(A, low, high, size);
quicksort_fn_hoare(A, low, partitionIndex - 1, size);
quicksort_fn_hoare(A, partitionIndex, high, size);
}
}
/**
* hoare_rt_pvt - the hoare partitioning scheme for quick sort
* @A: array of integers
* @left: partition start index
* @right: partition last index
* @size: size of the array
*
* Return: the
*/
int hoare_rt_pvt(int A[], int left, int right, size_t size)
{
int pivot, i, j;
pivot = A[right]; /* The last element */
i = left - 1;
j = right + 1;
while (i < j)
{
/* move i right till it A[i] is >= pivot if at all */
while (A[++i] < pivot)
;
/* move j left till it A[j] is <= pivot if at all */
while (A[--j] > pivot)
;
/**
* Have i and j crossed? Then the A partition is complete
* We return j because it is the rightmost index of the left
* partition i.e before pivot.
* The position of the pivot may or may not be the j + 1
* and so makes that unreliable. This also makes the position
* of i unreliable as well.
*/
/**
* A[i] and A[j] are on the wrong sides of the pivot
* swap them
*/
if (i < j)
{
swap(&A[i], &A[j]);
print_array(A, size);
}
}
return (i);
}
/**
* hoare_lf_pvt - the hoare partitioning scheme for quick sort
* @A: array of integers
* @left: partition start index
* @right: partition last index
* @size: size of the array
*
* Return: the
*/
int hoare_lf_pvt(int A[], int left, int right, size_t size)
{
int pivot, i, j;
pivot = A[left]; /* The last element */
i = left - 1;
j = right + 1;
while (1)
{
/* move i right till it A[i] is >= pivot if at all */
while (A[++i] < pivot)
;
/* move j left till it A[j] is <= pivot if at all */
while (A[--j] > pivot)
;
/**
* Have i and j crossed? Then the A partition is complete
* We return j because it is the rightmost index of the left
* partition i.e before pivot.
* The position of the pivot may or may not be the j + 1
* and so makes that unreliable. This also makes the position
* of i unreliable as well.
*/
if (i >= j)
return (j);
/**
* A[i] and A[j] are on the wrong sides of the pivot
* swap them
*/
print_array(A, size);
swap(&A[i], &A[j]);
}
}
/**
* swap - swaps two integer pointers
* @x: first int variable
* @y: second int variable
*
* Return: void
*/
void swap(int *x, int *y)
{
int tm;
tm = *x;
*x = *y;
*y = tm;
}