A run in a string is a substring of length at least two, as long as possible and consisting entirely of the same symbol. For instance, the string abbbaab contains a run of b's of length three and a run of a's of length two. Find dfa's for the following languages on {a,b}.
(a) L= {w: w contains no runs of length less than four}.
(b) L= {w: every run of a’s has length either two or three}.
(c) L= {w: there are at most two runs of a’s of length three}.
(d) L= {w: there are exactly two runs of a’s of length 3}.
