gnsstk::Combinations Class Reference

Detailed Description

Class Combinations will compute C(n,k), all the combinations of n things taken k at a time (where k <= n). Let n 'things' be indexed by i (i=0...n-1), e.g. stored in an array of length n. This class computes C(n,k) as sets of k indexes into the 'things' array. These indexes are accessible via member functions Selection() or isSelected(). Next() computes the next combination until there are no more (when it returns -1).

Definition at line 58 of file Combinations.hpp.

#include <Combinations.hpp>

Public Member Functions
	Combinations (const Combinations &right) noexcept
	copy constructor More...
	Combinations (int N, int K)
	Combinations (void) noexcept
	Default constructor. More...
bool	isSelected (int j) noexcept
int	Next (void) noexcept
Combinations &	operator= (const Combinations &right) noexcept
	Assignment operator. More...
int	Selection (int j) noexcept

Private Member Functions
int	Increment (int j) noexcept
	Recursive function to increment Index[j]. More...
void	init (int N, int K)

Private Attributes
std::vector< int >	Index
int	k
int	n
	combinations of n things taken k at a time More...
int	nc
	number of combinations computed so far More...

Constructor & Destructor Documentation

Combinations() [1/3]

gnsstk::Combinations::Combinations ( void  )

inlinenoexcept

Default constructor.

Definition at line 61 of file Combinations.hpp.

Combinations() [2/3]

gnsstk::Combinations::Combinations ( int  N, int  K  )

inline

Constructor for C(n,k) = combinations of n things taken k at a time (k <= n)

Exceptions

Exception

on invalid input (k>n).

Definition at line 69 of file Combinations.hpp.

Combinations() [3/3]

gnsstk::Combinations::Combinations ( const Combinations &  right )

inlinenoexcept

copy constructor

Definition at line 73 of file Combinations.hpp.

Member Function Documentation

Increment()

int gnsstk::Combinations::Increment ( int  j )

inlineprivatenoexcept

Recursive function to increment Index[j].

Definition at line 133 of file Combinations.hpp.

init()

void gnsstk::Combinations::init ( int  N, int  K  )

inlineprivate

The initialization routine used by constructors.

Exceptions

Exception

on invalid input (k>n or either n or k < 0).

Definition at line 117 of file Combinations.hpp.

isSelected()

bool gnsstk::Combinations::isSelected ( int  j )

inlinenoexcept

Return true if the given index j (0 <= j < n) is currently selected (i.e. if j = Selection(i) for some i)

Definition at line 106 of file Combinations.hpp.

Next()

int gnsstk::Combinations::Next ( void  )

inlinenoexcept

Compute the next combination, returning the number of combinations computed so far; if there are no more combinations, return -1.

Definition at line 90 of file Combinations.hpp.

operator=()

Combinations& gnsstk::Combinations::operator= ( const Combinations &  right )

inlinenoexcept

Assignment operator.

Definition at line 80 of file Combinations.hpp.

Selection()

int gnsstk::Combinations::Selection ( int  j )

inlinenoexcept

Return index i (0 <= i < n) of jth selection (0 <= j < k); if j is out of range, return -1.

Definition at line 98 of file Combinations.hpp.

Member Data Documentation

Index

std::vector<int> gnsstk::Combinations::Index

private

Index[j] = index of jth selection (j=0...k-1; I[j]=0...n-1)

Definition at line 150 of file Combinations.hpp.

k

int gnsstk::Combinations::k

private

Definition at line 149 of file Combinations.hpp.

n

int gnsstk::Combinations::n

private

combinations of n things taken k at a time

Definition at line 149 of file Combinations.hpp.

nc

int gnsstk::Combinations::nc

private

number of combinations computed so far

Definition at line 148 of file Combinations.hpp.

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The documentation for this class was generated from the following file:

• Combinations.hpp