library(tidyverse)
library(readxl)
path = "Excel/800-899/841/841 Sum of Alternate Signs Series.xlsx"
input = read_excel(path, range = "A1:A10")
test = read_excel(path, range = "B1:B10") %>% pull()
agg = function(n) if(n %% 2 == 0) n / 2 + 2 else (3 - n) / 2
result = map_dbl(input$N, agg)
all.equal(result, test)
# [1] TRUEExcel BI - Excel Challenge 841
excel-challenges
excel-formulas
🔰 Find the result of the series from 1 through n where + and - signs will alternate.
Challenge Description
🔰 Find the result of the series from 1 through n where + and - signs will alternate.
Solutions
- Logic: Read the workbook ranges needed for the challenge.
- Strengths: The code maps the workbook rule into a compact, reproducible pipeline.
- Areas for Improvement: The solution assumes the workbook layout and selected ranges remain stable, so any structural change in the sheet would require small adjustments.
- Gem: The elegant part is how little code is needed once the correct intermediate representation is chosen.
import pandas as pd
import numpy as np
path = "800-899/841/841 Sum of Alternate Signs Series.xlsx"
input_df = pd.read_excel(path, usecols="A", nrows=10)
test = pd.read_excel(path, usecols="B", nrows=10).iloc[:, 0].to_numpy()
def agg(n):
return n / 2 + 2 if n % 2 == 0 else (3 - n) / 2
result = np.array([agg(n) for n in input_df.iloc[:, 0]])
print(np.allclose(result, test))
# TrueThe Python version keeps the algorithm explicit, which helps when the challenge depends on a greedy or iterative rule.
Difficulty Level
Easy / Medium
The business rule is clear, though the workbook still needs a few transformation steps to reach the expected output.