// switch box routing

#include <iostream.h>
#include "stack.h"

bool CheckBox(int net[], int n)
{// Determine whether the switch box is routable.
	Stack<int> *s = new Stack<int>(n);
	
	// scan nets clockwise
	for (int i = 0; i < n; i++) 
	{
		// examine net[i]
		if (!s->IsEmpty()) 
		{// check with top net
			if (net[i] == net[s->Top()]) 
			{
				// net[i] routable, delete from stack
				int x;
				s->Delete(x);
			}
			else s->Add(i);
		}
		else 
			s->Add(i);
	}
	
	// any unrouted nets left?
	if (s->IsEmpty()) 
	{// no nets remain
		delete s;
		cout << "Switch box is routable" << endl;
		return true;
	}
	
	delete s;
	cout << "Switch box is not routable" << endl;
	return false;
}

void main(void)
{
	int *net, n;
	cout << "Type number of pins in switch box " << endl;
	cin >> n;
	try
	{
		net = new int[n];
		cout << "Type net numbers for pins 1 through " << n << endl;
		for (int i = 0; i<n; i++) cin >> net[i];
		CheckBox(net, n);
	}
	catch (NoMem)
	{
		cout << "Insufficient memory" << endl;
	}
}