Question

Construct DFA containing all string starting with 01 and having 012 as substring.

Answer 1

• In this, string does not begin with 012 and 12, when we get 01 we move to another state.  
• On that state we get any number of 01 (self-circle), and we cannot acknowledge 12 there however when we get 012 we move to another state as 012 is sub-string.  
• Same thing like point 2 is going toward happen till definite state.  
• N = dead state.  
• Least string that is acknowledged by this DFA is {0101212}.