std::nth_element
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| Defined in header <algorithm>
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| template< class RandomIt > void nth_element( RandomIt first, RandomIt nth, RandomIt last ); |
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| template< class RandomIt, class Compare > void nth_element( RandomIt first, RandomIt nth, RandomIt last, Compare comp ); |
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部分排序的范围内
[first, last)升序排列，使范围内的所有元素[first, nth)是“少”的范围内[nth, last)。 operator<的第一个版本使用比较的元素，第二个版本使用给定的比较函数comp。的元件放置在nth位置是完全相同的元素，该元素将在这个位置上，如果发生的范围完全排序.Original:
Partially sorts the range
[first, last) in ascending order so that all elements in the range [first, nth) are less than those in the range [nth, last). The first version uses operator< to compare the elements, the second version uses the given comparison function comp. The element placed in the nth position is exactly the element that would occur in this position if the range was fully sorted.The text has been machine-translated via Google Translate.
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目录 |
[编辑] 参数
| first, last | - | 随机访问迭代器定义的范围进行排序
Original: random access iterators defining the range sort The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. | |||||||||
| nth | - | 随机访问迭代器定义排序分割点
Original: random access iterator defining the sort partition point The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. | |||||||||
| comp | - | comparison function which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:
The signature does not need to have const &, but the function must not modify the objects passed to it. | |||||||||
| Type requirements | |||||||||||
-RandomIt must meet the requirements of ValueSwappable and RandomAccessIterator.
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-The type of dereferenced RandomIt must meet the requirements of MoveAssignable and MoveConstructible.
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[编辑] 返回值
（无）
Original:
(none)
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[编辑] 复杂性
线性平均在std::distance(first, last).
Original:
Linear in std::distance(first, last) on average.
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[编辑] 为例
#include <iostream> #include <vector> #include <algorithm> #include <functional> int main() { std::vector<int> v{5, 6, 4, 3, 2, 6, 7, 9, 3}; std::nth_element(v.begin(), v.begin() + v.size()/2, v.end()); std::cout << "The median is " << v[v.size()/2] << '\n'; std::nth_element(v.begin(), v.begin()+1, v.end(), std::greater<int>()); std::cout << "The second largest element is " << v[1] << '\n'; }
Output:
The median is 5 The second largest element is 7
[编辑] 另请参阅
| 副本和部分的范围内的元素进行排序 Original: copies and partially sorts a range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板） | |
| 排序范围内的元素，同时保持相等的元素之间的顺序 Original: sorts a range of elements while preserving order between equal elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板） | |
| 为升序排序范围 Original: sorts a range into ascending order The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板） | |
