void subtract(const Multiset& ms1, const Multiset& ms2, Multiset& result)
{
//make sure result is empty
if (result.size() != 0)
{
Multiset temp;
result = temp;
}
for (int m1 = 0; m1 < ms1.uniqueSize(); m1++)
{
ItemType m1_val;
int n1 = ms1.get(m1, m1_val);
for (int m2 = 0; m2 < ms2.uniqueSize(); m2++)
{
ItemType m2_val;
int n2 = ms2.get(m2, m2_val);
if (m1_val == m2_val && n1 > n2)
{
for (int count = n1-n2; count > 0; count--) //insert n1-n2 number of iterations
result.insert(m1_val);
}
}
}
}
void subtract(const Multiset& ms1, const Multiset& ms2, Multiset& result)
{
if (&ms2 == &result) //If ms2 and result are the same object, then modifications to result change ms2, so a copy of ms2 has to be made
{
Multiset temp = ms2;
result = ms1;
//temp and result are NOT the same object, so temp remains the same for each iteration of the loop
for (int i = 0; i < temp.uniqueSize(); i++)
{
ItemType item;
int count = temp.get(i, item);
for (int j = 0; j < count; j++)
result.erase(item);
}
}
else //ms2 and result are NOT the same object, so ms2 remains the same for each iteration of the loop
{
result = ms1;
//If ms1 and result are the same object, nothing happens
for (int i = 0; i < ms2.uniqueSize(); i++)
{
ItemType item;
int count = ms2.get(i, item);
for (int j = 0; j < count; j++)
result.erase(item);
}
}
}
void combine(const Multiset& ms1, const Multiset& ms2, Multiset& result)
{
bool addFirst = false; //addFirst indicates whether the contents of ms1 should be added to result
bool addSecond = false; //addSecond does the same, but for ms2
if (&ms1 == &result) //As result is ms1, only need to add ms2 to result to combine the two
addSecond = true;
else if (&ms2 == &result) //As result is ms2, only need to add ms1 to result to combine the two
addFirst = true;
else //Empty out result, as it may have contained something prior to this
{
int size = result.uniqueSize();
for (int i = 0; i < size; i++)
{
ItemType item;
result.get(0, item);
result.eraseAll(item);
}
addFirst = true;
addSecond = true;
}
if (addFirst) //ms1 and result are NOT the same object, so ms1.uniqueSize() remains the same for each iteration of the loop
{
for (int j = 0; j < ms1.uniqueSize(); j++)
{
ItemType item;
int count = ms1.get(j, item);
for (int k = 0; k < count; k++)
result.insert(item);
}
}
if (addSecond) //ms2 and result are NOT the same object, so ms2.uniqueSize() remains the same for each iteration of the loop
{
for (int j = 0; j < ms2.uniqueSize(); j++)
{
ItemType item;
int count = ms2.get(j, item);
for (int k = 0; k < count; k++)
result.insert(item);
}
}
}
void combine(const Multiset& ms1, const Multiset& ms2, Multiset& result)
{
result = ms1;
for (int k = 0; k < ms2.uniqueSize(); k++) //loop through ms2 and insert into result
{
ItemType x;
int n = ms2.get(k, x);
for (int count = n; count > 0; count--) //insert all iterations of value
result.insert(x);
}
}
int main(void)
{
Multiset ms;
ms.insert("fennel");
ms.insert("fennel");
ms.insert("fenugreek");
ms.insert("fennel");
for (int k = 0; k < ms.uniqueSize(); k++)
{
string x;
int n = ms.get(k, x);
cout << x << " occurs " << n << " times." << endl;
}
}