2075.py

# 2075. Decode the Slanted Ciphertext
# see  more about this on leetcode this include image from which you will get better idea about this problem


class Solution:
    def decodeCiphertext(self, encodedText: str, rows: int) -> str:
        if rows == 1:
            return encodedText
        
        n = len(encodedText)
        cols = n // rows
        
        matrix = []
        idx = 0
        for r in range(rows):
            matrix.append(list(encodedText[idx:idx + cols]))
            idx += cols
        
        result = []
        for start_col in range(cols):
            r, c = 0, start_col
            while r < rows and c < cols:
                result.append(matrix[r][c])
                r += 1
                c += 1
        
        return "".join(result).rstrip()


#  test case
if __name__ == "__main__":
    sol = Solution()
    
    print(sol.decodeCiphertext("ch   ie   pr", 3))  # expected: "cipher"
    print(sol.decodeCiphertext("iveo    eed   l te   olc", 4))  # expected: "i love leetcode"
    print(sol.decodeCiphertext("coding", 1))  # expected: "coding"