RandIter _MergeSort(RandIter first, RandIter mid, RandIter last, SortPred pred)
{
if (first < mid) { // At least two elements
// Divide and conquer
_MergeSort(first, first + (mid - first) / 2, mid, pred);
_MergeSort(mid, mid + (last - mid) / 2, last, pred);
// Merge
using ValueT = typename std::iterator_traits<RandIter>::value_type;
std::vector<ValueT> part1(first, mid);
std::vector<ValueT> part2(mid, last);
std::merge(part1.begin(), part1.end(), part2.begin(), part2.end(), first, pred);
#ifndef NDEBUG
std::cout << "[ ";
PrintSeq(first, mid, false);
std::cout << "]" << " + [ ";
PrintSeq(mid, last, false);
std::cout << "] --> [ ";
PrintSeq(first, last, false);
std::cout << "]\n";
#endif
}
return first;
}
int _MergeSort(int li, int ls) {
if(li==ls) return vec[ li ];
else {
int middle = (li+ls)>>1;
_MergeSort(li, middle);
_MergeSort(middle + 1, ls);
_merge(li, middle, ls);
}
};
RanIt MergeSort(RanIt first, RanIt last, Pred cmp)
{
#ifndef NDEBUG
std::cout << __func__ << ": ";
PrintSeq(first, last);
#endif
return _MergeSort(first, first + (last - first) / 2, last, cmp);
}
int main() {
read();
_MergeSort(0, n-1);
write();
return(0);
}
