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Decomp.cpp
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Decomp.cpp
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#include <iostream>
#include <string>
#include <math.h>
#include "Decomp.h"
using namespace std;
string Decomp::decompose(const string &nrStr, const string &drStr)
{
unsigned long long nom {correct_number(nrStr)}, denom {correct_number(drStr)};
if (nom == 0 || denom == 0)
{
return "[]";
}
string ret_val {"["};
if (nom > denom)
{
add_to_string(ret_val, 1, nom / denom);
nom = nom % denom;
}
if (nom > 1)
{
shorten_fraction(denom, nom);
}
unsigned long long k = 2;
while (nom > 1)
{
for (unsigned long long i = k; ; i++)
{
if (nom * i > denom)
{
k = i;
break;
}
}
substract_fraction(denom, nom, k);
add_to_string(ret_val, k);
k++;
}
if (nom > 0)
{
add_to_string(ret_val, denom, nom);
}
ret_val += "]";
return ret_val;
}
unsigned long long Decomp::correct_number(const string &nrStr)
{
unsigned long long ret_value = 0;
for (size_t i = 0, n = nrStr.size(); i < n; i++)
{
if (!isdigit(nrStr[i]))
{
return 0;
}
ret_value += static_cast<unsigned long long>(nrStr[i] - '0') * pow(10, n - i - 1);
}
return ret_value;
}
string Decomp::add_to_string(string &s_res, unsigned long long denom, unsigned long long nom)
{
if (s_res.size() > 1)
{
s_res += ", ";
}
s_res += to_string(nom);
if (denom > 1)
{
s_res += "/" + to_string(denom);
}
return s_res;
}
void Decomp::shorten_fraction(unsigned long long & denom, unsigned long long & nom)
{
for (unsigned long long k = 2, n = sqrt(nom); k < n; k++)
{
while (nom % k == 0 && denom % k == 0)
{
nom /= k;
denom /=k;
}
}
if (denom % nom == 0)
{
denom /= nom;
nom /= nom;
}
}
void Decomp::substract_fraction(unsigned long long & denom1, unsigned long long & nom1, unsigned long long denom2, unsigned long long nom2)
{
nom1 = nom1 * denom2 - nom2 * denom1;
denom1 *= denom2;
shorten_fraction(denom1, nom1);
}