28/06/2017 Traccia 1 Esercizio 3

Algo(G,a,b,c,d)
	Init(G)
	state = 0, foundB = False
	for each v € Adj(a):
		if not DFSmod(G,v,b,c,d,state,foundB)
			return False
	return True

DFSmod(G,v,b,c,d,state,foundB)
	col[v]=g
	if (v = c or v = d) and not foundB:
		state++
	else if v=b:
		foundB=True
	for each u € Adj(v):
		if col[u]=g:
			if foundB and state != 2:
				return False
		else if col[u]=b:
			if not DFSmod(G,u,b,c,d,state,foundB)
				return False
	col[v]=n
	return True