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Difference between revisions of "cpp/algorithm/ranges/set symmetric difference"

From cppreference.com
< cpp‎ | algorithm‎ | ranges
 
m (fmt)
 
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{{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::input_iterator I1, std::sentinel_for<I1> S1,
 
template< std::input_iterator I1, std::sentinel_for<I1> S1,
 
           std::input_iterator I2, std::sentinel_for<I2> S2,
 
           std::input_iterator I2, std::sentinel_for<I2> S2,
Line 10: Line 10:
 
           class Proj1 = std::identity, class Proj2 = std::identity >
 
           class Proj1 = std::identity, class Proj2 = std::identity >
 
requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
 
requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
−
constexpr ranges::set_symmetric_difference_result<I1, I2, O>
+
constexpr set_symmetric_difference_result<I1, I2, O>
−
ranges::set_symmetric_difference( I1 first1, S1 last1, I2 first2, S2 last2,
+
    set_symmetric_difference( I1 first1, S1 last1, I2 first2, S2 last2,
−
                                  O result, Comp comp = {},
+
                              O result, Comp comp = {},
−
                                  Proj1 proj1 = {}, Proj2 proj2 = {} );
+
                              Proj1 proj1 = {}, Proj2 proj2 = {} );
 
}}
 
}}
−
{{dcl | num=2 | since=c++20 |1=
+
{{dcl|num=2|since=c++20|1=
 
template< ranges::input_range R1, ranges::input_range R2,
 
template< ranges::input_range R1, ranges::input_range R2,
 
           std::weakly_incrementable O, class Comp = ranges::less,
 
           std::weakly_incrementable O, class Comp = ranges::less,
 
           class Proj1 = std::identity, class Proj2 = std::identity >
 
           class Proj1 = std::identity, class Proj2 = std::identity >
 
requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
 
requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
−
        O, Comp, Proj1, Proj2>
+
                        O, Comp, Proj1, Proj2>
−
constexpr ranges::set_symmetric_difference_result<
+
constexpr set_symmetric_difference_result<ranges::borrowed_iterator_t<R1>,  
−
          ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>, O>
+
                                          ranges::borrowed_iterator_t<R2>, O>
−
ranges::set_symmetric_difference( R1&& r1, R2&& r2, O result, Comp comp = {},
+
    set_symmetric_difference( R1&& r1, R2&& r2, O result, Comp comp = {},
−
                                  Proj1 proj1 = {}, Proj2 proj2 = {} );
+
                              Proj1 proj1 = {}, Proj2 proj2 = {} );
 
}}
 
}}
−
{{dcl h | Helper types}}
+
{{dcl h|Helper types}}
−
{{dcl | num=3 | since=c++20 |1=
+
{{dcl|num=3|since=c++20|1=
−
template<class I1, class I2, class O>
+
template< class I1, class I2, class O >
 
using set_symmetric_difference_result = ranges::in_in_out_result<I1, I2, O>;
 
using set_symmetric_difference_result = ranges::in_in_out_result<I1, I2, O>;
 
}}
 
}}
 
{{dcl end}}
 
{{dcl end}}
  
−
Computes symmetric difference of two sorted ranges: the elements that are found in either of the ranges, but not in both of them are copied to the range beginning at {{tt|result}}. The resulting range is also sorted.
+
Computes symmetric difference of two sorted ranges: the elements that are found in either of the ranges, but not in both of them are copied to the range beginning at {{c|result}}. The resulting range is also sorted.
  
−
If some element is found {{tt|m}} times in {{tt|[first1, last1)}} and {{tt|n}} times in {{tt|[first2, last2)}}, it will be copied to {{tt|result}} exactly {{tt|│m-n│}} times. If {{tt|m>n}}, then the last {{tt|m-n}} of those elements are copied from {{tt|[first1,last1)}}, otherwise the last {{tt|n-m}} elements are copied from {{tt|[first2,last2)}}. The resulting range cannot overlap with either of the input ranges.
+
If some element is found {{tt|m}} times in {{range|first1|last1}} and {{tt|n}} times in {{range|first2|last2}}, it will be copied to {{c|result}} exactly {{tt|│m - n│}} times. If {{tt|m > n}}, then the last {{tt|m - n}} of those elements are copied from {{range|first1|last1}}, otherwise the last {{tt|n - m}} elements are copied from {{range|first2|last2}}. The resulting range cannot overlap with either of the input ranges.
  
−
@1@ Elements are compared using the given binary comparison function {{tt|comp}}.
+
The behavior is undefined if
 +
* the input ranges are not sorted with respect to {{c|comp}} and {{c|proj1}} or {{c|proj2}}, respectively, or
 +
* the resulting range overlaps with either of the input ranges.
  
−
@2@ Same as {{v|1}}, but uses {{tt|r1}} as the first range and {{tt|r2}} as the second range, as if using {{c|ranges::begin(r1)}} as {{tt|first1}}, {{c|ranges::end(r1)}} as {{tt|last1}}, {{c|ranges::begin(r2)}} as {{tt|first2}}, and {{c|ranges::end(r2)}} as {{tt|last2}}.
+
@1@ Elements are compared using the given binary comparison function {{c|comp}}.
 +
 
 +
@2@ Same as {{v|1}}, but uses {{c|r1}} as the first range and {{c|r2}} as the second range, as if using {{c|ranges::begin(r1)}} as {{c|first1}}, {{c|ranges::end(r1)}} as {{c|last1}}, {{c|ranges::begin(r2)}} as {{c|first2}}, and {{c|ranges::end(r2)}} as {{c|last2}}.
  
−
''Preconditions:''
 
−
* The input ranges must be sorted with respect to {{tt|comp}} and {{tt|proj1}} or {{tt|proj2}}, respectively.
 
−
* The resulting range cannot overlap with either of the input ranges.
 
−
<br>
 
 
{{cpp/ranges/niebloid}}
 
{{cpp/ranges/niebloid}}
  
 
===Parameters===
 
===Parameters===
 
{{par begin}}
 
{{par begin}}
−
{{par | first1, last1 | the first input sorted range}}
+
{{par|first1, last1|iterator-sentinel pair denoting the first input sorted range}}
−
{{par | first2, last2 | the second input sorted range}}
+
{{par|first2, last2|iterator-sentinel pair denoting the second input sorted range}}
−
{{par | result | the beginning of the output range}}
+
{{par|r1|the first sorted input range}}
−
{{par | comp | comparison to apply to the projected elements}}
+
{{par|r2|the second sorted input range}}
−
{{par | proj1 | projection to apply to the elements in the first range}}
+
{{par|result|the beginning of the output range}}
−
{{par | proj2 | projection to apply to the elements in the second range.}}
+
{{par|comp|comparison to apply to the projected elements}}
 +
{{par|proj1|projection to apply to the elements in the first range}}
 +
{{par|proj2|projection to apply to the elements in the second range}}
 
{{par end}}
 
{{par end}}
  
 
===Return value===
 
===Return value===
−
An object equal to {{tt|{last1, last2, result_last},}} where {{tt|result_last}} is the end of the constructed range.
+
{{c|{last1, last2, result_last} }}, where {{c|result_last}} is the end of the constructed range.
  
 
===Complexity===
 
===Complexity===
−
At most {{c|1=2·(N₁+N₂)-1}} comparisons and applications of each projection, where <br>
+
At most {{mathjax-or|\(\scriptsize 2\cdot(N_1+N_2)-1\)|2&middot;(N{{su|b=1}}+N{{su|b=2}})-1}} comparisons and applications of each projection, where {{mathjax-or|\(\scriptsize N_1\)|N{{su|b=1}}}} and {{mathjax-or|\(\scriptsize N_2\)|N{{su|b=2}}}} are {{c|ranges::distance(first1, last1)}} and {{c|ranges::distance(first2, last2)}}, respectively.
−
{{c|1=N₁ = ranges::distance(first1, last1)}}, and
+
−
{{c|1=N₂ = ranges::distance(first2, last2)}}.
+
  
 
===Possible implementation===
 
===Possible implementation===
 
{{eq fun|1=
 
{{eq fun|1=
−
struct set_symmetric_difference_fn {
+
struct set_symmetric_difference_fn
−
     template< std::input_iterator I1, std::sentinel_for<I1> S1,
+
{
−
              std::input_iterator I2, std::sentinel_for<I2> S2,
+
     template<std::input_iterator I1, std::sentinel_for<I1> S1,
−
              std::weakly_incrementable O, class Comp = ranges::less,
+
            std::input_iterator I2, std::sentinel_for<I2> S2,
−
              class Proj1 = std::identity, class Proj2 = std::identity >
+
            std::weakly_incrementable O, class Comp = ranges::less,
 +
            class Proj1 = std::identity, class Proj2 = std::identity>
 
     requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
 
     requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
 
     constexpr ranges::set_symmetric_difference_result<I1, I2, O>
 
     constexpr ranges::set_symmetric_difference_result<I1, I2, O>
−
    operator()( I1 first1, S1 last1, I2 first2, S2 last2, O result, Comp comp = {},
+
        operator()(I1 first1, S1 last1, I2 first2, S2 last2, O result, Comp comp = {},
−
                Proj1 proj1 = {}, Proj2 proj2 = {} ) const {
+
                  Proj1 proj1 = {}, Proj2 proj2 = {}) const
−
         while (!(first1 == last1 or first2 == last2)) {
+
    {
 +
         while (!(first1 == last1 or first2 == last2))
 +
        {
 
             if (std::invoke(comp, std::invoke(proj1, *first1), std::invoke(proj2, *first2)))
 
             if (std::invoke(comp, std::invoke(proj1, *first1), std::invoke(proj2, *first2)))
−
                 *result = *first1, ++first1, ++result;
+
            {
−
             else if (std::invoke(comp, std::invoke(proj2, *first2), std::invoke(proj1, *first1)))
+
                 *result = *first1;
−
                 *result = *first2, ++first2, ++result;
+
                ++first1;
 +
                ++result;
 +
            }
 +
             else if (std::invoke(comp, std::invoke(proj2, *first2),
 +
                                      std::invoke(proj1, *first1)))
 +
            {
 +
                 *result = *first2;
 +
                ++first2;
 +
                ++result;
 +
            }
 
             else
 
             else
−
                 ++first1, ++first2;
+
            {
 +
                 ++first1;
 +
                ++first2;
 +
            }
 
         }
 
         }
 
         auto res1 {ranges::copy(std::move(first1), std::move(last1), std::move(result))};
 
         auto res1 {ranges::copy(std::move(first1), std::move(last1), std::move(result))};
Line 89: Line 104:
 
     }
 
     }
  
−
     template< ranges::input_range R1, ranges::input_range R2,
+
     template<ranges::input_range R1, ranges::input_range R2,
−
              std::weakly_incrementable O, class Comp = ranges::less,
+
            std::weakly_incrementable O, class Comp = ranges::less,
−
              class Proj1 = std::identity, class Proj2 = std::identity >
+
            class Proj1 = std::identity, class Proj2 = std::identity>
 
     requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
 
     requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
−
            O, Comp, Proj1, Proj2>
+
                            O, Comp, Proj1, Proj2>
 
     constexpr ranges::set_symmetric_difference_result<
 
     constexpr ranges::set_symmetric_difference_result<
−
              ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>, O>
+
        ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>, O>
−
    operator()( R1&& r1, R2&& r2, O result, Comp comp = {},
+
        operator()(R1&& r1, R2&& r2, O result, Comp comp = {},
−
                Proj1 proj1 = {}, Proj2 proj2 = {} ) const {
+
                  Proj1 proj1 = {}, Proj2 proj2 = {}) const
 +
    {
 
         return (*this)(ranges::begin(r1), ranges::end(r1),
 
         return (*this)(ranges::begin(r1), ranges::end(r1),
 
                       ranges::begin(r2), ranges::end(r2),
 
                       ranges::begin(r2), ranges::end(r2),
Line 105: Line 121:
 
};
 
};
  
−
inline constexpr set_symmetric_difference_fn set_symmetric_difference{};
+
inline constexpr set_symmetric_difference_fn set_symmetric_difference {};
 
}}
 
}}
  
 
===Example===
 
===Example===
 
{{example
 
{{example
−
| code=
+
|code=
 
#include <algorithm>
 
#include <algorithm>
 
#include <iostream>
 
#include <iostream>
Line 116: Line 132:
 
#include <vector>
 
#include <vector>
  
−
void visualize_this(const auto& v, int min = 1, int max = 9) {
+
void visualize_this(const auto& v, int min = 1, int max = 9)
−
     for (auto i{min}; i <= max; ++i) {
+
{
 +
     for (auto i {min}; i <= max; ++i)
 +
    {
 
         std::ranges::binary_search(v, i) ? std::cout << i : std::cout << '.';
 
         std::ranges::binary_search(v, i) ? std::cout << i : std::cout << '.';
 
         std::cout << ' ';
 
         std::cout << ' ';
Line 129: Line 147:
 
     const auto in2 = {1,    4, 5, 6,    9};
 
     const auto in2 = {1,    4, 5, 6,    9};
  
−
     std::vector<int> out;
+
     std::vector<int> out {};
  
 
     std::ranges::set_symmetric_difference(in1, in2, std::back_inserter(out));
 
     std::ranges::set_symmetric_difference(in1, in2, std::back_inserter(out));
Line 137: Line 155:
 
     visualize_this(out);
 
     visualize_this(out);
 
}
 
}
−
| output=
+
|output=
 
1 . 3 4 . 6 7 . 9
 
1 . 3 4 . 6 7 . 9
 
1 . . 4 5 6 . . 9
 
1 . . 4 5 6 . . 9
Line 145: Line 163:
 
===See also===
 
===See also===
 
{{dsc begin}}
 
{{dsc begin}}
−
{{dsc inc | cpp/algorithm/ranges/dsc set_union}}
+
{{dsc inc|cpp/algorithm/ranges/dsc set_union}}
−
{{dsc inc | cpp/algorithm/ranges/dsc set_difference}}
+
{{dsc inc|cpp/algorithm/ranges/dsc set_difference}}
−
{{dsc inc | cpp/algorithm/ranges/dsc set_intersection}}
+
{{dsc inc|cpp/algorithm/ranges/dsc set_intersection}}
−
{{dsc inc | cpp/algorithm/ranges/dsc includes}}
+
{{dsc inc|cpp/algorithm/ranges/dsc includes}}
−
{{dsc inc | cpp/algorithm/dsc set_symmetric_difference}}
+
{{dsc inc|cpp/algorithm/dsc set_symmetric_difference}}
 
{{dsc end}}
 
{{dsc end}}
  
 
{{langlinks|de|es|fr|it|ja|pt|ru|zh}}
 
{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

Latest revision as of 06:42, 16 April 2023

 
C++
 
Algorithm library
Constrained algorithms and algorithms on ranges (C++20)
Constrained algorithms, e.g. ranges::copy, ranges::sort, ...
Execution policies (C++17)
Non-modifying sequence operations
Batch operations
(C++17)
Search operations
(C++11)                (C++11)(C++11)

Modifying sequence operations
Copy operations
(C++11)
(C++11)
(C++11)
Swap operations
Transformation operations
Generation operations
Removing operations
Order-changing operations
(until C++17)(C++11)
(C++20)(C++20)
Sampling operations
(C++17)

Sorting and related operations
Partitioning operations
Sorting operations
Binary search operations
(on partitioned ranges)
Set operations (on sorted ranges)
Merge operations (on sorted ranges)
Heap operations
Minimum/maximum operations
(C++11)
(C++17)
Lexicographical comparison operations
(C++20)
Permutation operations
C library
Numeric operations
Operations on uninitialized memory
 
Constrained algorithms
All names in this menu belong to namespace std::ranges
Non-modifying sequence operations
Modifying sequence operations
Partitioning operations
Sorting operations
Binary search operations (on sorted ranges)
       
       
    
Set operations (on sorted ranges)
     
        
set_symmetric_difference

Heap operations
Minimum/maximum operations
       
       
Permutation operations
Fold operations
Numeric operations
(C++23)            
Operations on uninitialized storage
Return types
 
Defined in header <algorithm>
Call signature
template< std::input_iterator I1, std::sentinel_for<I1> S1,

          std::input_iterator I2, std::sentinel_for<I2> S2,
          std::weakly_incrementable O, class Comp = ranges::less,
          class Proj1 = std::identity, class Proj2 = std::identity >
requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
constexpr set_symmetric_difference_result<I1, I2, O>
    set_symmetric_difference( I1 first1, S1 last1, I2 first2, S2 last2,
                              O result, Comp comp = {},

                              Proj1 proj1 = {}, Proj2 proj2 = {} );
 (1) (since C++20)
template< ranges::input_range R1, ranges::input_range R2,

          std::weakly_incrementable O, class Comp = ranges::less,
          class Proj1 = std::identity, class Proj2 = std::identity >
requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
                        O, Comp, Proj1, Proj2>
constexpr set_symmetric_difference_result<ranges::borrowed_iterator_t<R1>,
                                          ranges::borrowed_iterator_t<R2>, O>
    set_symmetric_difference( R1&& r1, R2&& r2, O result, Comp comp = {},

                              Proj1 proj1 = {}, Proj2 proj2 = {} );
 (2) (since C++20)
Helper types
template< class I1, class I2, class O >
using set_symmetric_difference_result = ranges::in_in_out_result<I1, I2, O>;
 (3) (since C++20)

Computes symmetric difference of two sorted ranges: the elements that are found in either of the ranges, but not in both of them are copied to the range beginning at result. The resulting range is also sorted.

If some element is found m times in [first1, last1) and n times in [first2, last2), it will be copied to result exactly │m - n│ times. If m > n, then the last m - n of those elements are copied from [first1, last1), otherwise the last n - m elements are copied from [first2, last2). The resulting range cannot overlap with either of the input ranges.

The behavior is undefined if

  • the input ranges are not sorted with respect to comp and proj1 or proj2, respectively, or
  • the resulting range overlaps with either of the input ranges.
1) Elements are compared using the given binary comparison function comp.
2) Same as (1), but uses r1 as the first range and r2 as the second range, as if using ranges::begin(r1) as first1, ranges::end(r1) as last1, ranges::begin(r2) as first2, and ranges::end(r2) as last2.

The function-like entities described on this page are niebloids, that is:

In practice, they may be implemented as function objects, or with special compiler extensions.

Contents

[edit] Parameters

first1, last1 - iterator-sentinel pair denoting the first input sorted range
first2, last2 - iterator-sentinel pair denoting the second input sorted range
r1 - the first sorted input range
r2 - the second sorted input range
result - the beginning of the output range
comp - comparison to apply to the projected elements
proj1 - projection to apply to the elements in the first range
proj2 - projection to apply to the elements in the second range

[edit] Return value

{last1, last2, result_last}, where result_last is the end of the constructed range.

[edit] Complexity

At most 2·(N1+N2)-1 comparisons and applications of each projection, where N1 and N2 are ranges::distance(first1, last1) and ranges::distance(first2, last2), respectively.

[edit] Possible implementation

struct set_symmetric_difference_fn
{
    template<std::input_iterator I1, std::sentinel_for<I1> S1,
             std::input_iterator I2, std::sentinel_for<I2> S2,
             std::weakly_incrementable O, class Comp = ranges::less,
             class Proj1 = std::identity, class Proj2 = std::identity>
    requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
    constexpr ranges::set_symmetric_difference_result<I1, I2, O>
        operator()(I1 first1, S1 last1, I2 first2, S2 last2, O result, Comp comp = {},
                   Proj1 proj1 = {}, Proj2 proj2 = {}) const
    {
        while (!(first1 == last1 or first2 == last2))
        {
            if (std::invoke(comp, std::invoke(proj1, *first1), std::invoke(proj2, *first2)))
            {
                *result = *first1;
                ++first1;
                ++result;
            }
            else if (std::invoke(comp, std::invoke(proj2, *first2),
                                       std::invoke(proj1, *first1)))
            {
                *result = *first2;
                ++first2;
                ++result;
            }
            else
            {
                ++first1;
                ++first2;
            }
        }
        auto res1 {ranges::copy(std::move(first1), std::move(last1), std::move(result))};
        auto res2 {ranges::copy(std::move(first2), std::move(last2), std::move(res1.out))};
        return {std::move(res1.in), std::move(res2.in), std::move(res2.out)};
    }
 
    template<ranges::input_range R1, ranges::input_range R2,
             std::weakly_incrementable O, class Comp = ranges::less,
             class Proj1 = std::identity, class Proj2 = std::identity>
    requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
                            O, Comp, Proj1, Proj2>
    constexpr ranges::set_symmetric_difference_result<
        ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>, O>
        operator()(R1&& r1, R2&& r2, O result, Comp comp = {},
                   Proj1 proj1 = {}, Proj2 proj2 = {}) const
    {
        return (*this)(ranges::begin(r1), ranges::end(r1),
                       ranges::begin(r2), ranges::end(r2),
                       std::move(result), std::move(comp),
                       std::move(proj1), std::move(proj2));
    }
};
 
inline constexpr set_symmetric_difference_fn set_symmetric_difference {};

[edit] Example

Run this code
#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
 
void visualize_this(const auto& v, int min = 1, int max = 9)
{
    for (auto i {min}; i <= max; ++i)
    {
        std::ranges::binary_search(v, i) ? std::cout << i : std::cout << '.';
        std::cout << ' ';
    }
    std::cout << '\n';
}
 
int main()
{
    const auto in1 = {1, 3, 4,    6, 7, 9};
    const auto in2 = {1,    4, 5, 6,    9};
 
    std::vector<int> out {};
 
    std::ranges::set_symmetric_difference(in1, in2, std::back_inserter(out));
 
    visualize_this(in1);
    visualize_this(in2);
    visualize_this(out);
}

Output: 

1 . 3 4 . 6 7 . 9
1 . . 4 5 6 . . 9
. . 3 . 5 . 7 . .

[edit] See also

(C++20)
 computes the union of two sets
(niebloid)[edit]
(C++20)
 computes the difference between two sets
(niebloid)[edit]
(C++20)
 computes the intersection of two sets
(niebloid)[edit]
(C++20)
 returns true if one sequence is a subsequence of another
(niebloid)[edit]
computes the symmetric difference between two sets
(function template) [edit]
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