1.
A variable name in a programming language must be either a letter or a letter followed by a decimal digit. How many different variable names are there in this language?
2.
(a) In how many ways can we make up the pattern
......x
x x x x x
......x
......x
......x------>這是十字型喔
with 0s and 1s?
(b) How many of part (a) patterns are not symmetrical with respect to the vertical axis?
想破頭了.....