const c = circuit(3);
c.h(0); c.h(1); c.h(2);

// Oracle for |101⟩: flip q1 (so all three are |1⟩), apply CCZ, flip q1 back.
// CCZ via H-CCX-H on the target qubit (q2).
for (let i = 0; i < 2; i++) {
  c.x(1);
  c.h(2);
  c.ccx(0, 1, 2);
  c.h(2);
  c.x(1);

  // Diffuser
  c.h(0); c.h(1); c.h(2);
  c.x(0); c.x(1); c.x(2);
  c.h(2);
  c.ccx(0, 1, 2);
  c.h(2);
  c.x(0); c.x(1); c.x(2);
  c.h(0); c.h(1); c.h(2);
}
return c;