Added magic eight ball.

Author: primaryobjects

even.py

@@ -3,6 +3,7 @@
 from lib.oracles.even import oracle
 
 def main():
+    # Find all even numbers in a given range.
     execute.provider = None
 
     # Generate the quantum circuit.

lib/oracles/numeric.py

@@ -0,0 +1,40 @@
+from qiskit import QuantumCircuit
+from qiskit.circuit.library.standard_gates.z import ZGate
+
+def oracle(i, n):
+    # Returns a quantum circuit that recognizes a single number i.
+    # Upon starting, all qubits are assumed to have a value of 1.
+    # We use a circuit of size n+1 to include an output qubit.
+    qc = QuantumCircuit(n+1)
+
+    # Convert i to a binary string.
+    bin_str = bin(i)[2:]
+
+    # Pad the binary string with zeros to the length of the qubits.
+    bin_str = bin_str.zfill(n)
+
+    print('Encoding ' + bin_str)
+
+    # Reverse the bits since qiskit represents the qubits from right to left.
+    bin_str = bin_str[::-1]
+
+    # Flip each qubit to zero to match the bits in the target number i.
+    for j in range(len(bin_str)):
+        if bin_str[j] == '0':
+            qc.x(j)
+
+    # Apply a controlled Z-gate on all qubits, setting the phase.
+    qc.append(ZGate().control(n), range(n+1))
+
+    # Undo each inverted qubit.
+    for j in range(len(bin_str)):
+        if bin_str[j] == '0':
+            qc.x(j)
+
+    print(qc.draw())
+
+    # Convert the oracle to a gate.
+    gate = qc.to_gate()
+    gate.name = "oracle"
+
+    return gate

magicball.py

@@ -0,0 +1,82 @@
+import random
+from math import ceil, log
+from lib.util import execute
+from lib.grover import grover
+from lib.oracles.numeric import oracle
+
+predictions = [
+    'It is certain.',
+    'It is decidedly so.',
+    'Without a doubt.',
+    'Yes definitely.',
+    'You may rely on it.',
+    'As I see it, yes.',
+    'Most likely.',
+    'Outlook good.',
+    'Yes.',
+    'Signs point to yes.',
+    'Reply hazy, try again.',
+    'Ask again later.',
+    'Better not tell you now.',
+    'Cannot predict now.',
+    'Concentrate and ask again.',
+    'Don''t count on it.',
+    'My reply is no.',
+    'My sources say no.',
+    'Outlook not so good.',
+    'Very doubtful.'
+]
+
+def main():
+    """
+    Return a random prediction from a dictionary, selecting the index using Grover's search.
+    Example:
+    Please ask me a yes/no question and I will predict your future [PRESS ANY KEY] ...
+
+    Selected random index 4
+    Encoding 00100
+
+    {'01000': 27, '01111': 27, '01110': 26, '11010': 31, '11001': 32, '00010': 27, '11101': 25, '10100': 27, '11100': 31, '11110': 24, '00111': 35, '01100': 31, '01010': 36, '10001': 30, '00011': 32, '00100': 135, '10011': 23, '00110': 25, '11111': 27, '10010': 23, '10110': 34, '10111': 34, '11000': 34, '00101': 36, '01001': 31, '10000': 19, '10101': 29, '00000': 26, '01011': 28, '00001': 23, '01101': 26, '11011': 30}
+    Result: 4 (00100)
+
+    You may rely on it.
+    """
+
+    execute.provider = None
+
+    input('Please ask me a yes/no question and I will predict your future [PRESS ANY KEY] ...')
+
+    # Determine the number of qubits required.
+    n = ceil(log(len(predictions), 2))
+
+    # Select a random prediction.
+    r = random.choice(range(len(predictions)))
+
+    print()
+    print('Selected random index ' + str(r))
+
+    # Generate the quantum circuit.
+    qc = grover(oracle, r, n)
+    print(qc.draw())
+
+    # Execute the quantum circuit.
+    result = execute(qc)
+
+    # Get the resulting hit counts.
+    counts = result.get_counts()
+    print(counts)
+
+    # Find the most frequent hit count.
+    key = max(counts, key=counts.get)
+
+    # Since the quantum computer returns a binary string (one bit for each qubit), we need to convert it to an integer.
+    index = int(key, 2)
+
+    print()
+    print('Result: ' + str(index) + ' (' + key + ')')
+
+    # Print the resulting prediction from the quantum circuit.
+    print()
+    print(predictions[index])
+
+main()

odd.py

@@ -3,6 +3,7 @@
 from lib.oracles.odd import oracle
 
 def main():
+    # Find all odd numbers in a given range.
     execute.provider = None
 
     # Generate the quantum circuit.