commit c5e00c07ab89bf743020c23806e2d1f4e48c9953
Author: Daniel Tsvetkov <danieltcv@gmail.com>
Date:   Sun Dec 30 10:31:00 2018 +0200

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
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--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+venv
+.idea
diff --git a/main.py b/main.py
new file mode 100644
index 0000000..4c728cc
--- /dev/null
+++ b/main.py
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+"""
+Naive cows and bulls brute force implementation.
+Generates all possible numbers in a pool
+"""
+import random
+
+
+def number_has_repeating_or_zero(number):
+    """
+    Check the digits in the number and if any is repeating or 0, return True, False otherwise
+    """
+    str_number = str(number)
+    used_numbers = []
+    for digit in str_number:
+        if digit == '0' or digit in used_numbers:
+            return True
+        used_numbers += [digit]
+    return False
+
+
+def count_cows(number, guess):
+    """
+    cows are how many digits in the guess are in the number but *NOT* correct position
+    """
+    cows = 0
+    for pos, digit in enumerate(number):
+        if digit in guess and digit != guess[pos]:
+            cows += 1
+    return cows
+
+
+def count_bulls(number, guess):
+    """
+    bulls are how many digits in the guess are the same and in the correct position
+    """
+    bulls = 0
+    for pos, digit in enumerate(number):
+        if digit == guess[pos]:
+            bulls += 1
+    return bulls
+
+
+def is_number_guess_cb_match(number, guess, cows, bulls):
+    """
+    The crux of the algo - the number and guess combo must match
+    the number of cows and bulls
+    """
+    guess_cows = count_cows(number, guess)
+    guess_bulls = count_bulls(number, guess)
+    return guess_cows == cows and guess_bulls == bulls
+
+
+def main():
+    """
+    Generate all non-digit-repeating possible numbers between 1111 and 9999 excluding 0
+    that means that the first possible is 1234 and last is 9876.
+    Then chose a random number from the pool as the first guess, wait for input for cows and bulls,
+    prune the pool from impossible matches and repeat until 4 bulls
+    """
+    number_pool = [i for i in range(1234, 9877) if not number_has_repeating_or_zero(i)]
+    assert len(number_pool) == 3024  # 9*8*7*6 = 3024
+
+    # input loop
+    done = False
+    print("Write cows and bulls as two digits separated by blank space, e.g. 2 0")
+    while not done:
+        print("There are {} options left. Press c to see them".format(len(number_pool)))
+        guess = random.choice(number_pool)
+        # input verification loop
+        while True:
+            guess_result = input("{} ?".format(guess))
+            guess_result = guess_result.strip().strip()
+            if guess_result in ['c', 'C']:
+                print(number_pool)
+                continue
+            # input verification - must be 2 digits between 0 and 4
+            splitted_guess = guess_result.split()
+            if len(splitted_guess) != 2:
+                print("wrong input")
+                continue
+            cows, bulls = splitted_guess
+            if not cows.isdigit() or not bulls.isdigit() or \
+                not 0 <= int(cows) <= 4 or not 0 <= int(bulls) <= 4:
+                print("wrong input")
+                continue
+            cows, bulls = int(cows), int(bulls)
+            if bulls == 4:
+                print("Done! Your number is {}".format(guess))
+                done = True
+                break
+            # generate new pool - all that don't match can't possibly be the number so eliminate them
+            number_pool = [x for x in number_pool if is_number_guess_cb_match(str(x), str(guess), cows, bulls)]
+            # do a new guess
+            break
+
+def test():
+    assert number_has_repeating_or_zero(1234) is False
+    assert number_has_repeating_or_zero(1123) is True
+    assert number_has_repeating_or_zero(1322) is True
+    assert number_has_repeating_or_zero(1233) is True
+    assert number_has_repeating_or_zero(1230) is True
+
+    assert count_cows("1234", "4321") == 4
+    assert count_cows("1234", "5678") == 0
+    assert count_cows("1234", "1258") == 0  # but 2 bulls
+    assert count_cows("1234", "6581") == 1
+    assert count_bulls("1234", "1234") == 4
+    assert count_bulls("1234", "1258") == 2
+    assert count_bulls("1234", "4321") == 0
+    assert count_bulls("1234", "4132") == 1
+
+
+if __name__ == '__main__':
+    test()
+    main()