It is required that the homework submitted by each student be
his/her own thoughts. Discussion with others about how to do the
assignment is acceptable, indeed encouraged. However, the final writing up
of the assignment should represent each student's understanding of the
problem and should not be copied from another student or other source.
In particular, this means you are not supposed to look for posted
solutions and copy them. The more you work out for yourself, the more
you will benefit from doing the homework assignments.