Off by one error in for/range. Previously if the computer chose a secret code of zero (all blacks) it would skip initialization entirely and the player would not be able to finish the puzzle. Alternatively, if the computer chose the highest secret code (e.g. all Red in a three color puzzle), the actual secret code would be initialized to one less (RRW).

60_Mastermind/python/mastermind.py

@@ -46,7 +46,7 @@ def main() -> None:
         print("Guess my combination ...")
         answer = int(possibilities * random.random())
         numeric_answer = [-1] * num_positions
-        for _ in range(0, answer):
+        for _ in range(0, answer + 1):
             numeric_answer = get_possibility(numeric_answer)
         # human_readable_answer = make_human_readable(numeric_answer, color_letters)
         while num_moves < 10 and not turn_over: