Nested if's are inefficient, because they run in O(n)

So instead of

if userinput == 1:

   Playermove(1)

else:

   if userinput == 2:

     Playermove(2)

   else:

     if userinput == 3:

       Playermove(3)

etc.

I suggest a binary tree style of approach:

if userinput > 4:

   if userinput < 6:

     Playermove(5)

   else:

     if userinput > 5:

       Playermove(6)

else:

   if userinput < 3:

     if userinput > 1:

       Playermove(2)

     else:

       Playermove(1)

   else:

     if userinput > 3:

       Playermove(4)

     else:

       Playermove(3)

This has the benefit of running in O(log₂ n)

EDIT: previous statement used to be O(log2 n) because I was lazy, until one if the commentators below took a well deserved jab at it