Python-сообщество

def graph(rebra,start):
	stack=[start]
	past=[]
	otvet=[]
	while len(stack)!=0:
		for q in rebra:
			if q[0]==q[1]:
				continue
			if q[0]==stack[0] and q not in past:
				stack.append(q[1])
				past.append(q)
			elif q[1]==stack[0] and q not in past:
				stack.append(q[0])
				past.append(q)
		otvet.append(stack.pop(0))
	return otvet
f=open("graph.in")
l=f.read()
s=l.split()
rebra_int=int(s[1])
start=int(s[2])
rebra=[]
q=3
while rebra_int!=0:
	rebra.append((int(s[q]),int(s[q+1])))
	q+=2
	rebra_int-=1
temp=graph(rebra,start)
temp.sort()
otvet=""
for q in temp:
	otvet=otvet+str(q)+" "
f1=open("graph.out","w")
f1.write(otvet)
f1.close()

class node():
    def __init__(self,ind):
        self.ind=ind
        self.done=0
        self.neib=[]
    def M(self):
        if not self.done:
            self.done=1
            for i in self.neib:
                i.M()

nnode=5
links=[[0,0],[0,1],[4,3]]
nodes=[node(i) for i in range(nnode)]
for i,j in links:
    nodes[i].neib.append(nodes[j])
    nodes[j].neib.append(nodes[i])
nodes[0].M()
print sorted([i.ind for i in nodes if i.done])