combinatorics.cpp File Reference

Functions
bool	get_next_combo_helper (vector< unsigned > &combo, unsigned max_num, unsigned pos, bool reset_rest)
bool	get_next_combo (vector< unsigned > &combo, unsigned k, unsigned n, bool first_combo)
void	get_rand_permutation (vector< unsigned > &perm, unsigned perm_size)
uint64_t	get_64_bit_factorial (unsigned n)
uint64_t	get64BitnUpperk (unsigned n, unsigned k)
bool	read_in_permutations (string file_name, vector< vector< unsigned > > &perms)

Function Documentation

uint64_t get64BitnUpperk	(	unsigned	n,
		unsigned	k
	)

Returns the value of n!/k! for the given integers.

No guarantees on what happens if there is an overflow.

Todo:

Figure out what should happen when an overflow happens.

Parameters

n	The denominator of the n!/k! term.
k	The numerator of the n!/k! term.

Returns

The value of n!/k! for the given integers.

uint64_t get_64_bit_factorial

(

unsigned

n

)

Returns n! for the given value of n.

If n is too large, it just returns the highest value stored in 64 bits.

Parameters

n	The value to take the factorial of.

Returns

The factorial value of the given value.

bool get_next_combo	(	vector< unsigned > &	combo,
		unsigned	k,
		unsigned	n,
		bool	first_combo
	)

bool get_next_combo_helper	(	vector< unsigned > &	combo,
		unsigned	max_num,
		unsigned	pos,
		bool	reset_rest
	)

Helper function for get_next combo.

Given a combination, a position, and whether we are at a reset, finds the next combo if one exists. This means incrementing the element at the given position if possible, and then resetting the remaining values to the smallest values left. If its not possible, it returns false.

Parameters

combo	The current combo which is updated to get the next combo.
max_num	The maximum element value.
pos	The current position.
reset_rest	Whether the combo should be reset starting from the given position.

Returns

If we successfully found the next combination.

void get_rand_permutation	(	vector< unsigned > &	perm,
		unsigned	perm_size
	)

bool read_in_permutations	(	string	file_name,
		vector< vector< unsigned > > &	perms
	)