Answer
This Automation will be of 4 states
Work Step by Step
finite-state automaton that recognizes the set of all bit strings that contain three consecutive $1s$.
Have four states, with only $s_3$ final.
For i = 0, 1, 2,
transition from $s_i$ to $s_i$+1 on input 1 but back to $s_0$ on input 0. Both transitions from $s_3$ are to itself.
