Transpose2026-04-24

My Solution: Exercism Transpose solution

Instructions

Transpose a list of strings so that rows become columns and shorter lines are padded with spaces only where needed.

Rules:

• Return an empty string for empty input.
• Preserve the shape implied by the longest line.
• Pad missing characters with spaces after trimming any trailing placeholder padding.

Solution

def transpose(text):
    if text == "":
        return ""

    lines = text.split('\n')

    max_len = 0
    for line in lines:
        max_len = max(max_len, len(line))

    transpose = []

    for col in range(max_len):
        new_row = ""
        for row in lines:
            if col < len(row):
                new_row += row[col]
            else:
                new_row += '~'

        new_row = new_row.rstrip("~")
        new_row = new_row.replace("~", " ")

        transpose.append(new_row)

    return "\n".join(transpose)

Syntax Notes

• The early return handles the empty-input edge case directly.
• The placeholder character ~ makes it easy to distinguish real characters from padded gaps before converting them to spaces.
• The outer loop builds each output row by walking one column at a time across the input lines.