std::ranges::make_heap - cppreference.com (original) (raw)

Constructs a heap with respect to comp and proj from the elements in the specified range.

1. The specified range is [first, last).

2. The specified range is r.

The function-like entities described on this page are algorithm function objects (informally known as niebloids), that is:

• Explicit template argument lists cannot be specified when calling any of them.
• None of them are visible to argument-dependent lookup.
• When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is inhibited.

[edit] Parameters

[edit] Return value

1. last

[edit] Complexity

At most \(\scriptsize 3\cdot N\)3·N applications of comp and \(\scriptsize 6\cdot N\)6·N applications of proj, where \(\scriptsize N \)N is:

[edit] Example

#include #include #include #include #include   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(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); }

Output:

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

[edit] See also