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factored out internal_array_separate(..) to check if it has the errors or not

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This commit is contained in:
Richard Thier 2022-08-16 11:44:34 +02:00
parent 680936f50a
commit fbea1e607c
1 changed files with 38 additions and 22 deletions
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60
space_partitioning_sort/spsort.h
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@ -72,6 +72,41 @@ inline uint32_t internal_mid(uint32_t low, uint32_t high) {
/** Sort using space-partitioning - does recursive re-pivoting */ /** Sort using space-partitioning - does recursive re-pivoting */
inline void spsort(uint32_t *t, int n, int m = 32); inline void spsort(uint32_t *t, int n, int m = 32);
struct lr {
int left;
int right;
};
inline struct lr internal_array_separate(uint32_t *t, int n, uint32_t low, uint32_t mid, uint32_t high) {
// Init left-right "write head" indices
int left = 0;
int right = n - 1;
uint32_t current = t[left];
bool current_is_left = true;
// Separate to the ends of the array (in-place)
for(int i = 0; i < n; ++i) {
if(current < mid) {
const auto tmp = t[left];
t[left++] = current;
current = current_is_left ? t[left] : tmp;
current_is_left = true;
} else {
const auto tmp = t[right];
t[right--] = current;
current = tmp;
current = !current_is_left ? t[right] : tmp;
current_is_left = false;
}
}
struct lr eler;
eler.left = left;
eler.right = right;
return eler;
}
// TODO: [spsort] In-place variant that looks like a quicksort-kind-of-thing: // TODO: [spsort] In-place variant that looks like a quicksort-kind-of-thing:
// - I realized that in-placing make this similar to quicksort actually // - I realized that in-placing make this similar to quicksort actually
@ -98,28 +133,9 @@ inline void internal_spsort(uint32_t *t, int n, int m, uint32_t low, uint32_t mi
binsertion_sort(t, n); binsertion_sort(t, n);
} }
// Init left-right "write head" indices struct lr eler = internal_array_separate(t, n, low, mid, high);
int left = 0; auto left = eler.left;
int right = n - 1; auto right = eler.right;
uint32_t current = t[left];
bool current_is_left = true;
// Separate to the ends of the array (in-place)
for(int i = 0; i < n; ++i) {
if(current < mid) {
const auto tmp = t[left];
t[left++] = current;
current = current_is_left ? t[left] : tmp;
current_is_left = true;
} else {
const auto tmp = t[right];
t[right--] = current;
current = tmp;
current = !current_is_left ? t[right] : tmp;
current_is_left = false;
}
}
auto lefts = left; auto lefts = left;
auto rights = right - left; auto rights = right - left;