Solution 3
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        1) The pointer information of q(q ->  z) is reached at the in of
           the statement if(*q). Therefore, copy propagation takes place
           and *q is replaced by variable z. The optimization is correct
           as q->z and is not modified before reaching statement if(*q).

        2) In  program 2,  The  pointer information  reaching  at in  of
           statement are q->z  and q->y. Therefore, *q in  if(*q) can be
           replaced by z  or y. Copy propagation is suppressed  as we do
           not  have  definite  points-to  information  for  q  reaching
           statement if(*q).