2022-10-09 05:13:17 +00:00
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#ifndef _RSTL_ALGORITHM
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#define _RSTL_ALGORITHM
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2022-08-13 12:57:38 +00:00
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2022-09-18 05:55:13 +00:00
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#include "rstl/pointer_iterator.hpp"
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2022-08-13 12:57:38 +00:00
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namespace rstl {
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2022-10-04 00:00:46 +00:00
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template < class It, class T >
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inline It find(It first, It last, const T& val) {
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2022-09-18 05:55:13 +00:00
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while (first != last && !(*first == val))
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++first;
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return first;
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2022-08-13 12:57:38 +00:00
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}
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2022-10-04 00:00:46 +00:00
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template < typename T >
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inline void swap(T& a, T& b) {
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T tmp(a);
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a = b;
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b = tmp;
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}
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template < typename I1, typename I2 >
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inline void iter_swap(I1 a, I2 b) {
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swap(*a, *b);
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}
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2022-11-27 03:04:19 +00:00
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template < typename It, class Cmp >
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void __insertion_sort(It first, It last, Cmp cmp);
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template < class T, class Cmp >
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void __sort3(T& a, T& b, T& c, Cmp comp); // TODO
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template < typename It, class Cmp >
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void sort(It first, It last, Cmp cmp); // TODO
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// Implementations
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2022-10-04 00:00:46 +00:00
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template < typename It, class Cmp >
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2022-11-27 03:04:19 +00:00
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void __insertion_sort(It first, It last, Cmp cmp) {
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for (It next = first + 1; next < last; ++next) {
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typename iterator_traits< It >::value_type value = *next;
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2022-11-28 15:00:16 +00:00
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It t1 = next - 1;
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It t2 = next;
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while (first < t2 && cmp(value, *t1)) {
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*t2-- = *t1--;
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}
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*t2 = value;
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2022-11-27 03:04:19 +00:00
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}
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}
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template < typename T, class Cmp >
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void __sort3(T& a, T& b, T& c, Cmp comp) {
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if (comp(b, a)) {
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swap(a, b);
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}
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if (comp(c, b)) {
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T tmp(c);
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c = b;
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if (comp(tmp, a)) {
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b = a;
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a = tmp;
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} else {
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b = tmp;
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}
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}
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}
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template < typename It, class Cmp >
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void sort(It first, It last, Cmp cmp) {
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2022-11-27 21:58:19 +00:00
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int count = last - first; // use distance?
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2022-11-27 03:04:19 +00:00
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if (count > 1) {
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if (count <= 20) {
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__insertion_sort(first, last, cmp);
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} else {
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2022-11-28 16:03:59 +00:00
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It pivot = first + count / 2;
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2022-11-28 00:40:31 +00:00
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It end = last;
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2022-11-28 16:03:59 +00:00
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__sort3(*first, *pivot, *--end, cmp);
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typename iterator_traits< It >::value_type value = *pivot;
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2022-11-27 03:04:19 +00:00
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It it = first + 1;
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2022-11-28 00:40:31 +00:00
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--end;
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2022-11-27 03:04:19 +00:00
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while (true) {
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2022-11-27 21:58:19 +00:00
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while (cmp(*it, value))
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++it;
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2022-11-28 00:40:31 +00:00
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while (cmp(value, *end))
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--end;
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if (it >= end)
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break;
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iter_swap(it++, end--);
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2022-11-27 03:04:19 +00:00
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}
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sort(first, it, cmp);
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sort(it, last, cmp);
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}
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}
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}
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2022-09-18 05:55:13 +00:00
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} // namespace rstl
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2022-10-04 00:00:46 +00:00
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2022-10-09 05:13:17 +00:00
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#endif // _RSTL_ALGORITHM
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