Nonogram Row Nonogram Row

The ' nonogaram ' an exceptional mind-sharpening grid puzzle which requires for you to identify all cells in the grid as 'filled' or 'empty'.

For this mission you are given a row (String) and the number clues (list of Integers), so you will have to work with just one line. Each number clue represents the length of filled cells which will appear in that exact order.
If you'll manage to identify more filled or empty cells, reflect them in the input string and return it. If the row and number clues don't match, return None.


  • Symbol details:
    • '?' : unknown cell.
    • 'O' : filled cell.
    • 'X' : empty cell.


nonogram_row('??????????', [8]) == '??OOOOOO??'
nonogram_row('???O????O?', [3, 1]) == 'X??O??XXOX'
nonogram_row('????X?X???', [3, 2]) == '?OO?XXX?O?'
nonogram_row('???X?', [0]) == 'XXXXX'
nonogram_row('?????', []) == 'XXXXX'
nonogram_row('??X??', [3]) is None

Input: two arguments, an input row (String), and the number clues (list of Integers)

Output: the result row (String) or None

How it is used:
The actual nonogaram puzzle consists of multiple rows and also have number clues for the columns. All nonogram puzzles are designed in a way that all of the cells are identified as 'filled' or 'empty' with the help of the given number clues.



  • all(r in ('?', 'O', 'X') for r in row_string)
  • all(0 ≤ cn ≤ len(row_string) for cn in clue_numbers)
  • sum(clue_numbers) + len(clue_numbers) - 1 ≤ len(row_string)

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