ladybird/AK/QuickSort.h
2019-06-07 11:46:02 +02:00

42 lines
816 B
C++

#pragma once
#include <AK/StdLibExtras.h>
namespace AK {
template<typename T>
bool is_less_than(const T& a, const T& b)
{
return a < b;
}
template<typename Iterator, typename LessThan>
void quick_sort(Iterator start, Iterator end, LessThan less_than = is_less_than)
{
int size = end - start;
if (size <= 1)
return;
int pivot_point = size / 2;
auto pivot = *(start + pivot_point);
if (pivot_point)
swap(*(start + pivot_point), *start);
int i = 1;
for (int j = 1; j < size; ++j) {
if (less_than(*(start + j), pivot)) {
swap(*(start + j), *(start + i));
++i;
}
}
swap(*start, *(start + i - 1));
quick_sort(start, start + i - 1, less_than);
quick_sort(start + i, end, less_than);
}
}
using AK::quick_sort;