std::set_union
From Cppreference
| Defined in header <algorithm>
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| template< class InputIterator1, class InputIterator2, class OutputIterator >
OutputIterator set_union( InputIterator1 first1, InputIterator1 last1, |
(1) | |
| template< class InputIterator1, class InputIterator2,
class OutputIterator, class Compare > |
(2) | |
Constructs a sorted range beginning at d_first consisting of all elements present in one or both sorted ranges [first1, last1) and [first2, last2). The first version expects both input ranges to be sorted with operator<, the second version expects them to be sorted with the given comparison function comp. If some element is found m times in [first1, last1) and n times in [first2, last2), then all m elements will be copied from [first1, last1) to d_first, preserving order, and then exactly std::max(n-m, 0) elements will be copied from [first2, last2) to d_first, also preserving order. The resulting range cannot overlap with either of the input ranges.
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[edit] Parameters
| first1, last1 | - | the first input sorted range | |||||||||
| first2, last2 | - | the second input sorted range | |||||||||
| 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. |
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[edit] Return value
Iterator past the end of the constructed range.
[edit] Complexity
At most 2·(N1+N2-1) comparisons, where N1 = std::distance(first1, last1) and N2 = std::distance(first2, last2).
[edit] Equivalent function
| First version |
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template<class InputIterator1, class InputIterator2, class OutputIterator> OutputIterator set_union(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator d_first) { for (; first1 != last1; ++d_first) { if (first2 == last2) return std::copy(first1, last1, d_first); if (*first2 < *first1) { *d_first = *first2++; } else { *d_first = *first1; if (!(*first1 < *first2)) ++first2; ++first1; } } return std::copy(first2, last2, d_first); } |
| Second version |
template<class InputIterator1, class InputIterator2, class OutputIterator, class Compare> OutputIterator set_union(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator d_first, Compare comp) { for (; first1 != last1; ++d_first) { if (first2 == last2) return std::copy(first1, last1, d_first); if (comp(*first2, *first1)) { *d_first = *first2++; } else { *d_first = *first1; if (!comp(*first1, *first2)) ++first2; ++first1; } } return std::copy(first2, last2, d_first); } |
[edit] Example
| This section is incomplete |
[edit] See also
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returns true if one set is a subset of another (function template) |
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computes the difference between two sets (function template) |
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computes the intersection of two sets (function template) |
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computes the symmetric difference between two sets (function template) |
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