[ASD] RIC-IT 28/06/2017

/*
ALGO(T,P)
	flag= 0
	ret= 0
	if T != NIL then
		if T->key % 2 = 0 then
			flag= 1
		x= ALGO(T->sx, T)
		y= ALGO(T->dx, T)

		if flag=1 AND P != NIL AND x+y=0 then
			if P->sx= T then
				P->sx= CANCELLA-ROOT(T)
			else
				P->dx= CANCELLA-ROOT(T)
		ret= x+y+flag
	return ret
*/

ALGO_IT(T, P)
	currT= T, currP= P, last=nextT=nextP= NIL
	ret=flag=0
	S_T= S_P= S_flag= S_x= NIL

	while (currT != NIL || S_T != NIL) do
		if (currT != NIL) then
			ret= 0
			flag= 0

			if (currT->key % 2 == 0) then
				flag= 1

			push(S_T, currT)
			push(S_P, currP)
			push(S_flag, flag)
			nextT= currT->sx
			nextP= currT

		else
			currT= top(S_T)
			currP= top(S_P)
			flag= top(S_flag)

			if (last != currT->dx && currT->dx != NIL) then
				x= ret
				push(S_x, x)
				nextT= currT->dx
				nextP= currT

			else
				pop(S_T)
				pop(S_P)
				pop(S_flag)
				x= top(S_x)
				pop(S_x)

				if (currT->dx != NIL) then
					y= ret
				else
					y= 0

				if (flag == 1 && currP != NIL && x+y= 0) then
					if (currP->sx == currT) then
						currP->sx= CANCELLA-ROOT(currT)
					else
						currP->dx= CANCELLA-ROOT(currT)
				ret= x+y+flag
				nextT= NIL

		last= currT
		currT= nextT
		currP= nextP

	return ret