Difference between revisions of "cpp/algorithm/partial sort copy"
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Revision as of 21:45, 31 May 2013
| Defined in header <algorithm>
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| template< class InputIt, class RandomIt > RandomIt partial_sort_copy( InputIt first, InputIt last, |
(1) | |
| template< class InputIt, class RandomIt, class Compare > RandomIt partial_sort_copy( InputIt first, InputIt last, |
(2) | |
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
Template:par req concept Template:par req concept Template:par req concept deref | ||
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
See also
| sorts the first N elements of a range (function template) | |
| sorts a range into ascending order (function template) | |
| sorts a range of elements while preserving order between equal elements (function template) |
