binomial_calculate.cpp File Reference

Program to calculate Binomial coefficients More...

#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <iostream>

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Namespaces
namespace	math
	for IO operations
namespace	binomial
	Functions for Binomial coefficients implementation.

Functions
size_t	math::binomial::calculate (int32_t n, int32_t k)
	Function to calculate binomial coefficients.
static void	tests ()
	Test implementations.
int	main (int argc, const char *argv[])
	Main function.

Detailed Description

Program to calculate Binomial coefficients

Author

astronmax

Function Documentation

calculate()

size_t math::binomial::calculate	(	int32_t	n,
		int32_t	k )

Function to calculate binomial coefficients.

Parameters

n	first value
k	second value

Returns

binomial coefficient for n and k

                                       {
    // basic cases
    if (k > (n / 2))
        k = n - k;
    if (k == 1)
        return n;
    if (k == 0)
        return 1;
 
    size_t result = 1;
    for (int32_t i = 1; i <= k; ++i) {
        result *= n - k + i;
        result /= i;
    }
 
    return result;
}

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main()

int main	(	int	argc,
		const char *	argv[] )

Main function.

Parameters

argc	commandline argument count
argv	commandline array of arguments

Returns

0 on exit

                                       {
    tests();  // run self-test implementations
 
    if (argc < 3) {
        std::cout << "Usage ./binomial_calculate {n} {k}" << std::endl;
        return 0;
    }
 
    int32_t n = atoi(argv[1]);
    int32_t k = atoi(argv[2]);
 
    std::cout << math::binomial::calculate(n, k) << std::endl;
    return 0;
}

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tests()

static void tests ( )

static

Test implementations.

Returns

void

                    {
    // tests for calculate function
    assert(math::binomial::calculate(1, 1) == 1);
    assert(math::binomial::calculate(57, 57) == 1);
    assert(math::binomial::calculate(6, 3) == 20);
    assert(math::binomial::calculate(10, 5) == 252);
    assert(math::binomial::calculate(20, 10) == 184756);
    assert(math::binomial::calculate(30, 15) == 155117520);
    assert(math::binomial::calculate(40, 20) == 137846528820);
    assert(math::binomial::calculate(50, 25) == 126410606437752);
    assert(math::binomial::calculate(60, 30) == 118264581564861424);
    assert(math::binomial::calculate(62, 31) == 465428353255261088);
 
    std::cout << "[+] Binomial coefficients calculate test completed"
              << std::endl;
}

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