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C++ mergesort with iterators
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#include <algorithm> | |
#include <iostream> | |
#include <list> | |
#include <vector> | |
template<typename Iter> | |
void print(const Iter& beg, const Iter& end, bool new_line = true) | |
{ | |
std::for_each(beg, end, [](auto& i) { std::cout << i << " "; }); | |
if (new_line) { | |
std::cout << std::endl; | |
} | |
} | |
template<typename Iter> | |
void merge(Iter beg, Iter mid, Iter end) | |
{ | |
std::vector<typename Iter::value_type> temp; | |
temp.reserve(std::distance(beg, end)); | |
std::cout << "merge "; print(beg, mid, false); std::cout << "↔ "; print(mid, end); | |
Iter left = beg; | |
Iter right = mid; | |
while (left != mid and right != end) { | |
if (*right < *left) { | |
temp.emplace_back(*right++); | |
} | |
else { | |
temp.emplace_back(*left++); | |
} | |
} | |
temp.insert(temp.end(), left, mid); | |
temp.insert(temp.end(), right, end); | |
std::move(temp.begin(), temp.end(), beg); | |
std::cout << " ⇒ "; print(beg, end); | |
} | |
template<typename Iter> | |
void merge_sort(Iter beg, Iter end) | |
{ | |
std::cout << "sort "; print(beg, end); | |
int size = std::distance(beg, end); | |
if (size <= 1) { | |
return; | |
} | |
auto mid = std::next(beg, size / 2); | |
// sort left half | |
merge_sort(beg, mid); | |
// sort right half | |
merge_sort(mid, end); | |
// merge halves | |
merge(beg, mid, end); | |
} | |
int main(int argc, const char* argv[]) | |
{ | |
std::list<int> l = {2, 5, 1, 7, 9, 2, 4, 3, 8, 11}; | |
merge_sort(l.begin(), l.end()); | |
std::cout << "done "; print(l.begin(), l.end()); | |
return 0; | |
} |
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