We introduce four hidden states:
s2 = u0 + u1
s3 = u1 + u2
s0 = u2 + u3
s1 = u3 + u0.
When considering the parity-check matrix
|   1 1 1 0   1 0 0 0   | |
H |
|   1 0 1 1   0 0 1 0   | |
|   0 1 1 1   0 0 0 1   | |
we see that the parity-check equations can be written as follows
x4 = u2 + s2
x5 = u1 + s1
x6 = u0 + s0
x7 = u3 + s3.
This yields the following realization: