Difference between revisions of "cpp/algorithm/partial sort copy"
m (Text replace - "RandomAccessIterator" to "RandomIt") |
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{{ddcl list item | num=1 | | {{ddcl list item | num=1 | | ||
template< class InputIt, class RandomIt > | template< class InputIt, class RandomIt > | ||
| − | RandomIt partial_sort_copy( InputIt first, | + | RandomIt partial_sort_copy( InputIt first, InputIt last, |
| − | + | RandomIt d_first, RandomIt d_last ); | |
| − | + | ||
| − | + | ||
}} | }} | ||
{{ddcl list item | num=2 | | {{ddcl list item | num=2 | | ||
template< class InputIt, class RandomIt, class Compare > | template< class InputIt, class RandomIt, class Compare > | ||
| − | RandomIt partial_sort_copy( InputIt first, | + | RandomIt partial_sort_copy( InputIt first, InputIt last, |
| − | + | RandomIt d_first, RandomIt d_last, | |
| − | + | Compare comp ); | |
| − | + | ||
| − | + | ||
}} | }} | ||
{{ddcl list end}} | {{ddcl list end}} | ||
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{{param list item | d_first, d_last | random access iterators defining the destination range}} | {{param list item | d_first, d_last | random access iterators defining the destination range}} | ||
{{param list cmp | comp | p1=RandomIt}} | {{param list cmp | comp | p1=RandomIt}} | ||
| + | {{param list hreq}} | ||
| + | {{param list req concept | InputIt | InputIterator}} | ||
| + | {{param list req concept | RandomIt | RandomAccessIterator}} | ||
{{param list end}} | {{param list end}} | ||
Revision as of 04:49, 3 August 2012
Template:ddcl list begin <tr class="t-dsc-header">
<td><algorithm>
<td></td> <td></td> </tr> <tr class="t-dcl ">
<td >RandomIt partial_sort_copy( InputIt first, InputIt last,
<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">
<td >RandomIt partial_sort_copy( InputIt first, InputIt last,
RandomIt d_first, RandomIt d_last,
<td > (2) </td> <td class="t-dcl-nopad"> </td> </tr> Template:ddcl list end
Sorts some of the elements in the range [first, last) in ascending order. At most d_first - d_last of the elements are moved to the range [d_first, d_first + n) and then sorted. n is the number of elements to sort (n = min(last - first, d_last - d_first)). The order of equal elements is not guaranteed to be preserved. The first version uses operator< to compare the elements, the second version uses the given comparison function comp.
Contents |
Parameters
| first, last | - | the range of elements to sort |
| d_first, d_last | - | random access iterators defining the destination range |
| comp | - | comparison function object (i.e. an object that satisfies the requirements of Compare) which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following: bool cmp(const Type1& a, const Type2& b); While the signature does not need to have const&, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) |
| Type requirements | ||
-InputIt must meet the requirements of LegacyInputIterator.
| ||
-RandomIt must meet the requirements of LegacyRandomAccessIterator.
| ||
Return value
an iterator to the element defining the upper boundary of the sorted range, i.e. d_first + min(last - first, d_last - d_first).
Complexity
O(N·log(min(D,N)), where N = std::distance(first, last), D = std::distance(d_first, d_last) applications of cmp.
Example
The following code sorts an vector of integers and copies them into a smaller and a larger vector.
#include <algorithm> #include <vector> #include <functional> #include <iostream> int main() { std::vector<int> v0{4, 2, 5, 1, 3}; std::vector<int> v1{10, 11, 12}; std::vector<int> v2{10, 11, 12, 13, 14, 15, 16}; std::vector<int>::iterator it; it = std::partial_sort_copy(v0.begin(), v0.end(), v1.begin(), v1.end()); std::cout << "Writing to the smaller vector in ascending order gives: "; for (int a : v1) { std::cout << a << " "; } std::cout << '\n'; if(it == v1.end()) std::cout << "The return value is the end iterator\n"; it = std::partial_sort_copy(v0.begin(), v0.end(), v2.begin(), v2.end(), std::greater<int>()); std::cout << "Writing to the larger vector in descending order gives: "; for (int a : v2) { std::cout << a << " "; } std::cout << '\n' << "The return value is the iterator to " << *it << '\n'; }
Output:
Writing to the smaller vector in ascending order gives: 1 2 3 The return value is the end iterator Writing to the larger vector in descending order gives: 5 4 3 2 1 15 16 The return value is the iterator to 15
