std::ranges::make_heap
From cppreference.com
Defined in header <algorithm> | ||
Call signature | ||
template<std::random_access_iterator I, std::sentinel_for<I> S, class Comp =ranges::less, class Proj =std::identity> | (1) | (since C++20) |
template<ranges::random_access_range R, class Comp =ranges::less, class Proj =std::identity> | (2) | (since C++20) |
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.
Contents |
[edit]Parameters
first, last | - | the iterator-sentinel pair defining the range of elements to modify |
r | - | the range of elements to modify |
comp | - | comparator to apply to the projected elements |
proj | - | projection to apply to the elements |
[edit]Return value
1)last
2)ranges::end(r)
[edit]Complexity
At most 3·N applications of comp and 6·N applications of proj, where N is:
1)ranges::distance(first, last)
2)ranges::distance(r)
[edit]Example
Run this code
#include <algorithm>#include <cmath>#include <functional>#include <iostream>#include <vector> void out(constauto& what, int n =1){while(n-->0)std::cout<< what;} void print(auto rem, constauto& v){ out(rem);for(auto e : v) out(e), out(' '); out('\n');} void draw_heap(constauto& 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){constint n{1<< t};constint w{(1<<(m - t -1))-1}; bails(n, w), data(n, w, first, last);}; constint 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);}
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
(C++20) | checks if the given range is a max heap (algorithm function object) |
(C++20) | finds the largest subrange that is a max heap (algorithm function object) |
(C++20) | adds an element to a max heap (algorithm function object) |
(C++20) | removes the largest element from a max heap (algorithm function object) |
(C++20) | turns a max heap into a range of elements sorted in ascending order (algorithm function object) |
creates a max heap out of a range of elements (function template) |