Permutation instances

Instance of a permutation. More...

Classes
struct	tgen::permutation::instance
	Permutation instance. More...

Functions
	tgen::permutation::instance::instance (const std::vector< int > &vec)
	Creates a permutation instance from a std::vector.
int	tgen::permutation::instance::size () const
	Returns the size of the permutation instance.
int &	tgen::permutation::instance::operator[] (int idx)
	Returns the value at some position of the instance.
int	tgen::permutation::instance::parity () const
	Parity of the permutation.
instance &	tgen::permutation::instance::sort ()
	Sorts the instance in non-decreasing order.
instance &	tgen::permutation::instance::reverse ()
	Reverses the instance.
instance &	tgen::permutation::instance::inverse ()
	Inverse of the permutation.
instance &	tgen::permutation::instance::add_1 ()
	Adds 1 for printing.
std::vector< int >	tgen::permutation::instance::to_std () const
	Converts the instance to a std::vector.

Friends
std::ostream &	tgen::permutation::instance::operator<< (std::ostream &out, const instance &inst)
	Prints the instance to a std::ostream.

Detailed Description

Instance of a permutation.

It can be deterministically operated upon and printed through std::cout.

Function Documentation

add_1()

instance & tgen::permutation::instance::add_1 ( )

inline

Adds 1 for printing.

This makes it so, when given to std::cout, the permutation will be printed as 1-based.

Complexity

O(1).

Examples

// Prints a 1-based permutation.
tgen::permutation::instance inst = {2, 0, 1};
std::cout <<
    inst.add_1() << std::endl; // Prints "3 1 2".

Definition at line 1191 of file tgen.h.

instance()

tgen::permutation::instance::instance ( const std::vector< int > & vec )

inline

Creates a permutation instance from a std::vector.

Parameters

vec	The std::vector representing the instance.

Examples

// Creates and prints an instance from a std::vector.
std::vector<int> v = {0, 1, 2};
tgen::permutation::instance inst(v);
std::cout << inst << std::endl; // Prints "0 1 2".
 
// Also works with conversions, and std::initializer_list<T>.
inst = {1, 0};
std::cout << inst.add_1() << std::endl; // Prints "2 1".

Definition at line 1126 of file tgen.h.

inverse()

instance & tgen::permutation::instance::inverse ( )

inline

Inverse of the permutation.

The inverse of the permutation p is another pi such that pi[p[i]] = p[pi[i]] = i.

Complexity

O(n).

Examples

// Prints inverse of permutation.
tgen::permutation::instance inst = {2, 0, 1};
std::cout <<
    inst.inverse() << std::endl; // Prints "1 2 0".

Definition at line 1181 of file tgen.h.

operator[]()

int & tgen::permutation::instance::operator[] ( int idx )

inline

Returns the value at some position of the instance.

Parameters

idx	The index to be accessed.

Returns

The value at index idx.

Examples

// Prints a position of an instance.
tgen::permutation::instance inst = {2, 0, 1};
++inst[1];
std::cout << inst[1] << std::endl; // Prints "0".

Definition at line 1145 of file tgen.h.

parity()

int tgen::permutation::instance::parity ( ) const

inline

Parity of the permutation.

Returns

+1 if the permutation is even, or -1 if the permutation is odd.

Examples

// Prints parity of permutation.
tgen::permutation::instance inst = {2, 0, 1};
std::cout <<
    inst.parity() << std::endl; // Prints "1".

Definition at line 1150 of file tgen.h.

reverse()

instance & tgen::permutation::instance::reverse ( )

inline

Reverses the instance.

Complexity

O(n).

Examples

// Reverses and prints an instance.
tgen::permutation::instance inst = {2, 0, 1};
std::cout <<
    inst.reverse() << std::endl; // Prints "1 0 2".

Definition at line 1174 of file tgen.h.

size()

int tgen::permutation::instance::size ( ) const

inline

Returns the size of the permutation instance.

Returns

The size (number of elements) of the permutation instance.

Examples

// Prints the size of an instance.
tgen::permutation::instance inst = {0, 1, 2};
std::cout <<
    inst.size() << std::endl; // Prints "3".

Definition at line 1142 of file tgen.h.

sort()

instance & tgen::permutation::instance::sort ( )

inline

Sorts the instance in non-decreasing order.

Complexity

O(n).

Examples

// Sorts and prints an instance.
tgen::permutation::instance inst = {2, 0, 1};
std::cout <<
    inst.sort() << std::endl; // Prints "0 1 2".

Definition at line 1166 of file tgen.h.

to_std()

std::vector< int > tgen::permutation::instance::to_std ( ) const

inline

Converts the instance to a std::vector.

Returns

A std::vector representing the instance.

Examples

// Convoluted way to reverse a permutation.
std::vector<int> v = {2, 0, 1};
v = tgen::permutation::instance(v).reverse().to_std();
// v = {2, 1, 3}.

Definition at line 1208 of file tgen.h.

Friends

operator<<

std::ostream & operator<< ( std::ostream & out, const instance & inst )

friend

Prints the instance to a std::ostream.

The values are printed with one space as a separator, and with no end of line.

Examples

// Prints an instance.
std::cout <<
    tgen::permutation::instance({2, 0, 1}) << std::endl; // Prints "2 0 1".

Definition at line 1197 of file tgen.h.