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BAN: Cleanup intro_sort and quick_sort

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Only recurse to the smaller partition. This prevents worst case O(n)
recursion
This commit is contained in:
Bananymous
2026-07-07 04:43:06 +03:00
parent 896bb05073
commit 7b4b5a3440
1 changed files with 36 additions and 12 deletions
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48
BAN/include/BAN/Sort.h
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@@ -67,11 +67,20 @@ namespace BAN::sort
template<typename It, typename Comp = less<it_value_type_t<It>>>
void quick_sort(It begin, It end, Comp comp = {})
{
if (distance(begin, end) <= 1)
return;
const auto [lt, gt] = detail::partition(begin, end, comp);
quick_sort(begin, lt, comp);
quick_sort(gt, end, comp);
while (distance(begin, end) > 1)
{
const auto [lt, gt] = detail::partition(begin, end, comp);
if (distance(begin, lt) < distance(gt, end))
{
quick_sort(begin, lt);
begin = gt;
}
else
{
quick_sort(gt, end);
end = lt;
}
}
}
template<typename It, typename Comp = less<it_value_type_t<It>>>
@@ -102,13 +111,28 @@ namespace BAN::sort
template<typename It, typename Comp>
void intro_sort_impl(It begin, It end, size_t max_depth, Comp comp)
{
if (distance(begin, end) <= 16)
return insertion_sort(begin, end, comp);
if (max_depth == 0)
return heap_sort(begin, end, comp);
const auto [lt, gt] = detail::partition(begin, end, comp);
intro_sort_impl(begin, lt, max_depth - 1, comp);
intro_sort_impl(gt, end, max_depth - 1, comp);
for (size_t i = 0; i < max_depth; i++)
{
const size_t len = distance(begin, end);
if (len <= 1)
return;
if (len <= 16)
return insertion_sort(begin, end, comp);
const auto [lt, gt] = detail::partition(begin, end, comp);
if (distance(begin, lt) < distance(gt, end))
{
intro_sort_impl(begin, lt, max_depth - 1, comp);
begin = gt;
}
else
{
intro_sort_impl(gt, end, max_depth - 1, comp);
end = lt;
}
}
heap_sort(begin, end, comp);
}
}