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Commit e1a8b5e

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Implement partial_sort_copy.
1 parent 69927a3 commit e1a8b5e

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2 files changed

+65
-0
lines changed

2 files changed

+65
-0
lines changed

‎array_alg.h

Lines changed: 45 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -673,6 +673,15 @@ ALGDEF void NS(partial_sort)(
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void *compare_ctx
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);
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676+
ALGDEF T *NS(partial_sort_copy)(
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const T *first,
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const T *last,
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T *out_first,
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T *out_last,
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int (*compare)(const T*, const T*, void*),
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void *compare_ctx
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);
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676685
ALGDEF void NS(nth_element)(
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T *first,
678687
T *nth,
@@ -2109,6 +2118,42 @@ ALGDEF void NS(partial_sort)(
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NS(sort_heap)(first, middle, compare, compare_ctx);
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}
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2121+
ALGDEF T *NS(partial_sort_copy)(
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const T *first,
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const T *last,
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T *out_first,
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T *out_last,
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int (*compare)(const T*, const T*, void*),
2127+
void *compare_ctx
2128+
)
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{
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size_t n1 = last - first;
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size_t n2 = out_last - out_first;
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size_t n = (n2 < n1) ? n2 : n1;
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out_last = out_first + n;
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if (n == 0) { return out_last; }
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NS(copy_n)(first, n, out_first);
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first += n;
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NS(make_heap_n)(out_first, n, compare, compare_ctx);
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while (first != last)
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{
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if (compare(first, out_first, compare_ctx) < 0)
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{
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NS(pop_heap_n)(out_first, n, compare, compare_ctx);
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*(out_last - 1) = *first;
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NS(push_heap_n)(out_first, n, compare, compare_ctx);
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}
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++first;
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}
2153+
NS(sort_heap)(out_first, out_last, compare, compare_ctx);
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return out_last;
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}
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ALGDEF void NS(nth_element)(
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T *first,
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T *nth,

‎test/tests.c

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -589,6 +589,25 @@ void test_partial_sort() {
589589
}
590590
}
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void test_partial_sort_copy() {
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enum { N = 100 };
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int nums[N];
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for (int i = 0; i < N; ++i) {
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nums[i] = i;
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}
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for (int iteration = 0; iteration < 1000; ++iteration) {
600+
intv_random_shuffle(nums, nums + N);
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int top[10];
603+
intv_partial_sort_copy(nums, nums + N, top, top + 10, compare_int, NULL);
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for (int i = 0; i < 10; ++i) {
606+
assert(top[i] == i);
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}
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}
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}
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592611
typedef void (*SortFunc)(int*, int*, int (*cmp)(const int*, const int*, void*), void*);
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594613
static inline
@@ -811,6 +830,7 @@ int main() {
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printf("-- test_sort_partition -- \n"); test_sort_partition();
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printf("-- test_nth_element --\n"); test_nth_element();
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printf("-- test_partial_sort --\n"); test_partial_sort();
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printf("-- test_partial_sort_copy --\n"); test_partial_sort_copy();
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printf("-- test_heap_sort --\n"); test_heap_sort();
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printf("-- test_insertion_sort --\n"); test_insertion_sort();
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printf("-- test_stable_sort --\n"); test_stable_sort();

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