Omid - Challenge 238

data-challenges
advanced-exercises
🔰 For example, in the highlighted rows, there are 4 rows containing consecutive numbers.
Published

March 24, 2026

Illustration for Omid - Challenge 238

Challenge Description

🔰 For example, in the highlighted rows, there are 4 rows containing consecutive numbers.

Solutions

library(tidyverse)
library(readxl)

path = "files/200-299/238/CH-238 Consecutive Numbers.xlsx"
input = read_excel(path, range = "B2:B19")
test = read_excel(path, range = "D2:E19")

result = input %>%
  mutate(group = cumsum(Numbers - lag(Numbers, default = first(Numbers)) != 1)) %>%
  mutate(Count = ifelse(n() == 1, "-", as.character(n())), .by = group) %>%
  select(Numbers, Count)

all.equal(result, test) # One row is different

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Builds the intermediate columns that drive the final result

  • 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

path = "200-299/238/CH-238 Consecutive Numbers.xlsx"
input = pd.read_excel(path, usecols="B", skiprows=1, nrows=18)
test = pd.read_excel(path, usecols="D:E", skiprows=1, nrows=18).rename(columns=lambda col: col.replace('.1', ''))
test['Count'] = test['Count'].astype(str)

input.columns = ['Numbers']
g = (input['Numbers'] != input['Numbers'].shift(1) + 1).cumsum()
input['Count'] = input.groupby(g)['Numbers'].transform(lambda x: '-' if len(x)==1 else str(len(x)))
result = input[['Numbers', 'Count']]

print(result == test) # One row is different

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Aggregates or ranks values at the relevant grouping level

  • 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 business rule is readable, but the workbook still requires careful implementation to reach the expected layout.