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added comp argument and test for stability

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This commit is contained in:
Ahmet Inan 2024-03-08 13:00:40 +01:00
commit 389fcc3bd8
2 changed files with 37 additions and 18 deletions
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31
sort.hh
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@ -13,7 +13,18 @@ static void insertion_sort(TYPE *a, int n)
{
for (int i = 1, j; i < n; ++i) {
TYPE t = a[i];
for (j = i; j > 0 && a[j-1] > t; --j)
for (j = i; j > 0 && t < a[j-1]; --j)
a[j] = a[j-1];
a[j] = t;
}
}
template <typename TYPE, typename COMP>
static void insertion_sort(TYPE *a, int n, COMP comp)
{
for (int i = 1, j; i < n; ++i) {
TYPE t = a[i];
for (j = i; j > 0 && comp(t, a[j-1]); --j)
a[j] = a[j-1];
a[j] = t;
}
@ -25,7 +36,7 @@ static void insertion_sort(INDEX *p, TYPE *a, int n)
p[0] = 0;
for (int i = 1, j; i < n; ++i) {
TYPE t = a[i];
for (j = i; j > 0 && a[j-1] > t; --j) {
for (j = i; j > 0 && t < a[j-1]; --j) {
a[j] = a[j-1];
p[j] = p[j-1];
}
@ -38,27 +49,33 @@ template <typename TYPE, int MAX_N, int M = 32>
class MergeSort
{
TYPE tmp[MAX_N];
void merge(TYPE *a, int n, int left, int right, int end)
template <typename COMP>
void merge(TYPE *a, int n, int left, int right, int end, COMP comp)
{
if (right > n)
right = n;
if (end > n)
end = n;
for (int i = left, j = right, k = left; k < end; ++k)
tmp[k] = (i < right && (j >= end || a[i] <= a[j])) ? a[i++] : a[j++];
tmp[k] = (i >= right || (j < end && comp(a[j], a[i]))) ? a[j++] : a[i++];
}
public:
void operator()(TYPE *a, int n)
template <typename COMP>
void operator()(TYPE *a, int n, COMP comp)
{
for (int i = 0; i < n; i += M)
insertion_sort(a+i, i > n-M ? n-i : M);
insertion_sort(a+i, i > n-M ? n-i : M, comp);
for (int l = M; l < n; l *= 2) {
for (int i = 0; i < n; i += 2*l)
merge(a, n, i, i+l, i+2*l);
merge(a, n, i, i+l, i+2*l, comp);
for (int i = 0; i < n; ++i)
a[i] = tmp[i];
}
}
void operator()(TYPE *a, int n)
{
operator()(a, n, [](TYPE x, TYPE y){ return x < y; });
}
};
}

24
tests/sort_regression_test.cc
View file

@ -22,25 +22,27 @@ int main()
typedef std::default_random_engine generator;
typedef std::uniform_int_distribution<int> distribution;
auto rand = std::bind(distribution(1, MAX_N), generator(seed));
int a[MAX_N], b[MAX_N], c[MAX_N], d[MAX_N], e[MAX_N], f[MAX_N], g[MAX_N];
CODE::MergeSort<int, MAX_N> merge_sort;
typedef std::pair<int, int> Pair;
Pair a[MAX_N], b[MAX_N], c[MAX_N];
int d[MAX_N], e[MAX_N];
auto comp = [](Pair a, Pair b){ return a.second < b.second; };
CODE::MergeSort<Pair, MAX_N> merge_sort;
for (int loop = 0; loop < 1000000; ++loop) {
int size = rand();
for (int i = 0; i < size; ++i)
a[i] = b[i] = c[i] = d[i] = e[i] = rand();
std::sort(a, a+size);
CODE::insertion_sort(b, size);
a[i].first = b[i].first = c[i].first = e[i] = i;
for (int i = 0; i < size; ++i)
a[i].second = b[i].second = c[i].second = d[i] = rand();
std::stable_sort(a, a+size, comp);
CODE::insertion_sort(b, size, comp);
for (int i = 0; i < size; ++i)
assert(a[i] == b[i]);
merge_sort(c, size);
merge_sort(c, size, comp);
for (int i = 0; i < size; ++i)
assert(a[i] == c[i]);
CODE::insertion_sort(e, d, size);
for (int i = 0; i < size; ++i)
f[i] = i;
std::stable_sort(f, f+size, [d](int i, int j){ return d[i] < d[j]; });
CODE::insertion_sort(g, e, size);
for (int i = 0; i < size; ++i)
assert(f[i] == g[i]);
assert(a[i].first == e[i]);
}
std::cerr << "Sorting regression test passed!" << std::endl;
return 0;