**Input:** Three qubits (stored in an array of length 3) in an arbitrary three-qubit state 
$\alpha \ket{000} + \beta \ket{001} + \gamma \ket{010} + \delta \ket{011} + \epsilon \ket{100} + {\color{blue}\zeta}\ket{101} + {\color{blue}\eta}\ket{110} + \theta\ket{111}$.

**Goal:** Swap the states of second and third qubit if and only if the state of the first qubit is $\ket{1}$, that is, change the three-qubit state to $\alpha \ket{000} + \beta \ket{001} + \gamma \ket{010} + \delta \ket{011} + \epsilon \ket{100} + {\color{red}\eta}\ket{101} + {\color{red}\zeta}\ket{110} + \theta\ket{111}$.
