Omid - Challenge 304

data-challenges
advanced-exercises
🔰 Question Result AB-XYZ-CD AB-ZYX-CD 12-345-67 12-543-67 X-ABC-Y X-CBA-Y
Published

March 24, 2026

Illustration for Omid - Challenge 304

Challenge Description

🔰 Question Result AB-XYZ-CD AB-ZYX-CD 12-345-67 12-543-67 X-ABC-Y X-CBA-Y

Solutions

library(tidyverse)
library(readxl)

path = "files/300-399/304/CH-304 Reverse Substrings Between Dashes.xlsx"
input = read_excel(path, range = "B1:B6")
test  = read_excel(path, range = "C1:C6")

reverse_segments <- function(s) {
  str_replace_all(s, "(?<=-)\\w+(?=-)", 
                  ~str_c(rev(str_split(.x, "", simplify = TRUE)), collapse = ""))
}
result = input %>%
  mutate(Result = map_chr(Question, ~ reverse_segments(.)))
all.equal(result$Result, test$Result)
## [1] TRUE

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Builds the intermediate columns that drive the final result

    • Parses the text patterns directly instead of relying on manual cleanup

  • Strengths:

    • The R solution stays close to the workbook rule and keeps the transformation compact.

  • Areas for Improvement:

    • The code assumes the sheet structure and source ranges remain stable.

  • Gem:

    • The strongest part of the solution is choosing the right intermediate representation before shaping the final output.
import pandas as pd
import re

path = "300-399/304/CH-304 Reverse Substrings Between Dashes.xlsx"
input = pd.read_excel(path, usecols="B", nrows=6)
test = pd.read_excel(path, usecols="C", nrows=6)

input['Result'] = input.iloc[:, 0].apply(
    lambda s: re.sub(r'(?<=-)\w+(?=-)', lambda m: m.group(0)[::-1], s)
)
print(input['Result'].equals(test['Result'])) # True

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Parses the text patterns directly instead of relying on manual cleanup

  • Strengths:

    • The Python version follows the same rule in a direct dataframe-oriented implementation.

  • Areas for Improvement:

    • The code assumes the workbook layout remains stable, so any sheet redesign would require small adjustments.

  • Gem:

    • The implementation stays close to the original workbook rule instead of adding unnecessary abstraction.

Difficulty Level

This task is moderate:

  • The core logic is clear, but the correct transformation pattern is not obvious from the raw input.

  • The challenge combines multiple reshaping, grouping, or parsing steps.