Mystery Function

Mystery Function is a daily coding puzzle where your mission is to work out what a hidden Python function does to text in 7 rows or fewer.

Each day there's a secret function called f that transforms whatever text you give it. Type in any input and see the exact output, like f("cat") returning "atc". Once you think you've cracked the rule, tap I know it and switch from testing to predicting.

• Enter any text to test the function. Every try uses up a row.
• Tap I know it and you'll get new inputs, one at a time. Type the exact output you expect.
• Predictions get feedback per character. One marker means the right character in the right place, another means the right character in the wrong place, and the last means the character isn't in the output at all.
• A wrong prediction sends you back to testing, but any correct outputs still count.
• You need 2 correct outputs to win, and fewer rows means a better score.
• A new function appears every day.

Why we like it:

• ✅It turns spotting a pattern in code into a quick, satisfying detective game.
• ✅Character-level feedback shows you exactly how close your guess was.
• ✅Progress carries over after a miss, so a wrong prediction never wastes the round.

Hint: Start with inputs that reveal structure, like short words, repeated letters, and different lengths. A string such as "aab" tells you far more about the rule than a random word does.