gate1.py

from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector

def play_level(target, player_oracle_moves):
    qc = QuantumCircuit(2)
    qc.h([0, 1])
    
    # --- STEP 1: PLAYER'S ORACLE ---
    for gate in player_oracle_moves:
        if gate == 'X0': qc.x(0)
        if gate == 'X1': qc.x(1)
        if gate == 'CZ': qc.cz(0, 1)
    
    # --- CRITICAL RULE: UN-COMPUTATION ---
    # If the user doesn't un-flip the X gates here, 
    # the Diffuser will amplify the wrong state.
    
    # --- STEP 2: THE STANDARD DIFFUSER ---
    qc.h([0, 1])
    qc.x([0, 1])
    qc.h(1)
    qc.cx(0, 1) 
    qc.h(1)
    qc.x([0, 1])
    qc.h([0, 1])
    
    # --- STEP 3: RESULTS ---
    state = Statevector.from_instruction(qc)
    probs = state.probabilities_dict()
    win_prob = probs.get(target, 0)
    
    print(f"\nTesting Target {target} with moves {player_oracle_moves}")
    print(f"Probability of Target: {win_prob*100:.1f}%")
    
    # A successful Grover search must leave the qubits in the correct orientation
    if win_prob > 0.9:
        print("🏆 SUCCESS!")
    else:
        # Find what they actually found
        actual_find = max(probs, key=probs.get)
        print(f"💀 FAIL! You marked the wrong state or forgot to un-flip your X gates!")

        # --- START THE GAME ---

# This should FAIL because of the extra X0
play_level("11", ["X0", "CZ"]) 

# This should PASS because 11 needs no flipping
play_level("11", ["CZ"]) 

# This should FAIL because 01 needs an X1 to be seen by the CZ
play_level("01", ["CZ"])

# This should PASS because it flips the 0 to a 1, marks it, and flips it back
play_level("01", ["X1", "CZ", "X1"])