Difference between revisions of "cpp/algorithm/ranges/pop heap"
From cppreference.com
m (→Example: hardening the const-ness) |
m (Minor tweak.) |
||
| (5 intermediate revisions by 4 users not shown) | |||
| Line 2: | Line 2: | ||
{{cpp/algorithm/ranges/navbar}} | {{cpp/algorithm/ranges/navbar}} | ||
{{dcl begin}} | {{dcl begin}} | ||
| − | {{dcl header | algorithm}} | + | {{dcl header|algorithm}} |
{{dcl h|Call signature}} | {{dcl h|Call signature}} | ||
| − | {{dcl | num=1 | since=c++20 |1= | + | {{dcl|num=1|since=c++20|1= |
template< std::random_access_iterator I, std::sentinel_for<I> S, | template< std::random_access_iterator I, std::sentinel_for<I> S, | ||
class Comp = ranges::less, class Proj = std::identity > | class Comp = ranges::less, class Proj = std::identity > | ||
| − | requires std::sortable<I, Comp, Proj> | + | requires std::sortable<I, Comp, Proj> |
| − | constexpr I | + | constexpr I pop_heap( I first, S last, Comp comp = {}, Proj proj = {} ); |
| − | + | ||
}} | }} | ||
| − | {{dcl | num=2 | since=c++20 |1= | + | {{dcl|num=2|since=c++20|1= |
| − | template< ranges::random_access_range R, class Comp = ranges::less, | + | template< ranges::random_access_range R, |
| − | + | class Comp = ranges::less, class Proj = std::identity > | |
| − | requires std::sortable<ranges::iterator_t<R>, Comp, Proj> | + | requires std::sortable<ranges::iterator_t<R>, Comp, Proj> |
constexpr ranges::borrowed_iterator_t<R> | constexpr ranges::borrowed_iterator_t<R> | ||
| − | + | pop_heap( R&& r, Comp comp = {}, Proj proj = {} ); | |
}} | }} | ||
{{dcl end}} | {{dcl end}} | ||
| − | Swaps the | + | Swaps the first element and the last element of the specified [[cpp/algorithm#Heap operations|heap]] with respect to {{c|comp}} and {{c|proj}} and makes the subrange excluding the first position into a heap with respect to {{c|comp}} and {{c|proj}}. This has the effect of removing the first element from the specified heap. |
| − | @1@ | + | @1@ The specified heap is {{range|first|last}}. |
| − | @2@ | + | @2@ The specified heap is {{c|r}}. |
{{cpp/ranges/niebloid}} | {{cpp/ranges/niebloid}} | ||
| Line 30: | Line 29: | ||
===Parameters=== | ===Parameters=== | ||
{{par begin}} | {{par begin}} | ||
| − | {{par | first, last | the range of elements | + | {{par|first, last|the iterator and sentinel designating the range of elements to modify}} |
| − | {{par | r | + | {{par|r|the range of elements to modify}} |
| − | {{par | | + | {{par|comp|comparator to apply to the projected elements}} |
| − | {{par | proj | + | {{par|proj|projection to apply to the elements}} |
{{par end}} | {{par end}} | ||
===Return value=== | ===Return value=== | ||
| − | + | @1@ {{c|last}} | |
| + | @2@ {{c|ranges::end(r)}} | ||
===Complexity=== | ===Complexity=== | ||
| − | + | At most {{mathjax-or|\(\scriptsize 2\log{(N)}\)|2log(N)}} applications of {{c|comp}} and {{mathjax-or|\(\scriptsize 4\log{(N)}\)|4log(N)}} applications of {{c|proj}}, where {{mathjax-or|\(\scriptsize N \)|N}} is: | |
| − | + | @1@ {{c|ranges::distance(first, last)}} | |
| − | + | @2@ {{c|ranges::distance(r)}} | |
| − | {{ | + | |
===Example=== | ===Example=== | ||
| − | {{example|code= | + | {{example |
| + | |code= | ||
#include <algorithm> | #include <algorithm> | ||
#include <array> | #include <array> | ||
| Line 53: | Line 53: | ||
#include <string_view> | #include <string_view> | ||
| − | template <class I = int*> | + | template<class I = int*> |
void print(std::string_view rem, I first = {}, I last = {}, | void print(std::string_view rem, I first = {}, I last = {}, | ||
std::string_view term = "\n") | std::string_view term = "\n") | ||
{ | { | ||
| − | for (std::cout << rem; first != last; ++first) | + | for (std::cout << rem; first != last; ++first) |
std::cout << *first << ' '; | std::cout << *first << ' '; | ||
| − | |||
std::cout << term; | std::cout << term; | ||
} | } | ||
| Line 65: | Line 64: | ||
int main() | int main() | ||
{ | { | ||
| − | std::array v { 3, 1, 4, 1, 5, 9, 2, 6, 5, 3 }; | + | std::array v{3, 1, 4, 1, 5, 9, 2, 6, 5, 3}; |
print("initially, v: ", v.cbegin(), v.cend()); | print("initially, v: ", v.cbegin(), v.cend()); | ||
| − | + | ||
std::ranges::make_heap(v); | std::ranges::make_heap(v); | ||
print("make_heap, v: ", v.cbegin(), v.cend()); | print("make_heap, v: ", v.cbegin(), v.cend()); | ||
| − | + | ||
print("convert heap into sorted array:"); | print("convert heap into sorted array:"); | ||
| − | for (auto n {std::ssize(v)}; n >= 0; --n) { | + | for (auto n {std::ssize(v)}; n >= 0; --n) |
| + | { | ||
std::ranges::pop_heap(v.begin(), v.begin() + n); | std::ranges::pop_heap(v.begin(), v.begin() + n); | ||
print("[ ", v.cbegin(), v.cbegin() + n, "] "); | print("[ ", v.cbegin(), v.cbegin() + n, "] "); | ||
| Line 78: | Line 78: | ||
} | } | ||
} | } | ||
| − | | output= | + | |output= |
initially, v: 3 1 4 1 5 9 2 6 5 3 | initially, v: 3 1 4 1 5 9 2 6 5 3 | ||
make_heap, v: 9 6 4 5 5 3 2 1 1 3 | make_heap, v: 9 6 4 5 5 3 2 1 1 3 | ||
| Line 97: | Line 97: | ||
===See also=== | ===See also=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc inc | cpp/algorithm/ranges/dsc push_heap}} | + | {{dsc inc|cpp/algorithm/ranges/dsc push_heap}} |
| − | {{dsc inc | cpp/algorithm/ranges/dsc is_heap}} | + | {{dsc inc|cpp/algorithm/ranges/dsc is_heap}} |
| − | {{dsc inc | cpp/algorithm/ranges/dsc is_heap_until}} | + | {{dsc inc|cpp/algorithm/ranges/dsc is_heap_until}} |
| − | {{dsc inc | cpp/algorithm/ranges/dsc make_heap}} | + | {{dsc inc|cpp/algorithm/ranges/dsc make_heap}} |
| − | {{dsc inc | cpp/algorithm/ranges/dsc sort_heap}} | + | {{dsc inc|cpp/algorithm/ranges/dsc sort_heap}} |
| − | {{dsc inc | cpp/algorithm/dsc pop_heap}} | + | {{dsc inc|cpp/algorithm/dsc pop_heap}} |
{{dsc end}} | {{dsc end}} | ||
| + | |||
| + | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | ||
Latest revision as of 01:23, 14 October 2024
| 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) |
Swaps the first element and the last element of the specified heap with respect to comp and proj and makes the subrange excluding the first position into a heap with respect to comp and proj. This has the effect of removing the first element from the specified heap.
1) The specified heap is
[first, last).2) The specified heap is r.
The function-like entities described on this page are 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.
In practice, they may be implemented as function objects, or with special compiler extensions.
Contents |
[edit] Parameters
| first, last | - | the iterator and sentinel designating 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 2log(N) applications of comp and 4log(N) applications of proj, where N is:
1) ranges::distance(first, last)
2) ranges::distance(r)
[edit] Example
Run this code
#include <algorithm> #include <array> #include <iostream> #include <iterator> #include <string_view> template<class I = int*> void print(std::string_view rem, I first = {}, I last = {}, std::string_view term = "\n") { for (std::cout << rem; first != last; ++first) std::cout << *first << ' '; std::cout << term; } int main() { std::array v{3, 1, 4, 1, 5, 9, 2, 6, 5, 3}; print("initially, v: ", v.cbegin(), v.cend()); std::ranges::make_heap(v); print("make_heap, v: ", v.cbegin(), v.cend()); print("convert heap into sorted array:"); for (auto n {std::ssize(v)}; n >= 0; --n) { std::ranges::pop_heap(v.begin(), v.begin() + n); print("[ ", v.cbegin(), v.cbegin() + n, "] "); print("[ ", v.cbegin() + n, v.cend(), "]\n"); } }
Output:
initially, v: 3 1 4 1 5 9 2 6 5 3 make_heap, v: 9 6 4 5 5 3 2 1 1 3 convert heap into sorted array: [ 6 5 4 3 5 3 2 1 1 9 ] [ ] [ 5 5 4 3 1 3 2 1 6 ] [ 9 ] [ 5 3 4 1 1 3 2 5 ] [ 6 9 ] [ 4 3 3 1 1 2 5 ] [ 5 6 9 ] [ 3 2 3 1 1 4 ] [ 5 5 6 9 ] [ 3 2 1 1 3 ] [ 4 5 5 6 9 ] [ 2 1 1 3 ] [ 3 4 5 5 6 9 ] [ 1 1 2 ] [ 3 3 4 5 5 6 9 ] [ 1 1 ] [ 2 3 3 4 5 5 6 9 ] [ 1 ] [ 1 2 3 3 4 5 5 6 9 ] [ ] [ 1 1 2 3 3 4 5 5 6 9 ]
[edit] See also
| (C++20) |
adds an element to a max heap (niebloid) |
| (C++20) |
checks if the given range is a max heap (niebloid) |
| (C++20) |
finds the largest subrange that is a max heap (niebloid) |
| (C++20) |
creates a max heap out of a range of elements (niebloid) |
| (C++20) |
turns a max heap into a range of elements sorted in ascending order (niebloid) |
| removes the largest element from a max heap (function template) |
