Regular Language over {0, 1}
that is a set of all odd length strings that contain exactly two 0
.
What this language means?
Note language string can be consist of two 0
and any number of 1
such that total length of string is odd. There is no other restriction. 1
and 0
an appear in any order and in any pattern.
As we know even
+ odd
= odd
. So in string is consist of at least three length and odd number of 1
because number of 0
in string is two.
So regular expression should be something like: A
, where A, B, C, are substrings consist of only 0
B 0
C 1
and total number of 1
in A, B, C is odd, hence all can't be ^
(nul) in a expression.
Now because total number of 1
in A, B, C = odd, so it can be something like: either(1) two even and one odd
or (2) all three are odd
.
Note: a odd length string can't be null.
Regular Expression:
1(11)*01(11)*01(11)* + 1(11)*0(11)*0(11)* + (11)*01(11)*0(11)* + (11)*0(11)*01(11)*
// all odd A odd, B C even B odd, A C even A B even, C odd