std::ranges::make_heap

#include <algorithm>
#include <cmath>
#include <functional>
#include <iostream>
#include <vector>
 
void out(const auto& what, int n = 1)
{
 while (n-- > 0)
 std::cout << what;
}
 
void print(auto rem, const auto& v)
{
 out(rem);
 for (auto e : v)
 out(e), out(' ');
 out('\n');
}
 
void draw_heap(const auto& v)
{
 auto bails = [](int n, int w)
 {
 auto b = [](int w) { out("┌"), out("─", w), out("┴"), out("─", w), out("┐"); };
 if (!(n /= 2))
 return;
 for (out(' ', w); n-- > 0;)
 b(w), out(' ', w + w + 1);
 out('\n');
 };
 
 auto data = [](int n, int w, auto& first, auto last)
 {
 for (out(' ', w); n-- > 0 && first != last; ++first)
 out(*first), out(' ', w + w + 1);
 out('\n');
 };
 
 auto tier = [&](int t, int m, auto& first, auto last)
 {
 const int n{1 << t};
 const int w{(1 << (m - t - 1)) - 1};
 bails(n, w), data(n, w, first, last);
 };
 
 const int m{static_cast<int>(std::ceil (std::log2 (1 + v.size())))};
 auto first{v.cbegin()};
 for (int i{}; i != m; ++i)
 tier(i, m, first, v.cend());
}
 
int main()
{
 std::vector h{1, 6, 1, 8, 0, 3, 3, 9, 8, 8, 7, 4, 9, 8, 9};
 print("source: ", h);
 
 std::ranges::make_heap(h);
 print("\n" "max-heap: ", h);
 draw_heap(h);
 
 std::ranges::make_heap(h, std::greater {});
 print("\n" "min-heap: ", h);
 draw_heap(h);
}

source: 1 6 1 8 0 3 3 9 8 8 7 4 9 8 9
 
max-heap: 9 8 9 8 8 4 9 6 1 0 7 1 3 8 3
 9
 ┌───┴───┐
 8 9
 ┌─┴─┐ ┌─┴─┐
 8 8 4 9
┌┴┐ ┌┴┐ ┌┴┐ ┌┴┐
6 1 0 7 1 3 8 3
 
min-heap: 0 1 1 8 6 3 3 9 8 8 7 4 9 8 9
 0
 ┌───┴───┐
 1 1
 ┌─┴─┐ ┌─┴─┐
 8 6 3 3
┌┴┐ ┌┴┐ ┌┴┐ ┌┴┐
9 8 8 7 4 9 8 9