Step by Step solution about How to resolve the algorithm Five weekends step by step in the Julia programming language

The given code is a Julia program that finds months with 5 full weekends (Friday, Saturday, and Sunday) within a specified year range and calculates the number of years without at least one such month. Here's a detailed explanation:

Function isweekend:

• This function takes a Date object dt as input.
• It checks if the day of the week for dt is either Friday, Saturday, or Sunday using the Dates.dayofweek function.
• It returns true if dt is a weekend day and false otherwise.

Function hasfiveweekend:

• This function takes two integers month and year as input.
• It creates a date range dmin:dmax from the first day of the specified month and year to the last day of the same month.
• It applies the isweekend function to each date in the range, counting the number of weekend days using the count function.
• It returns true if the count is greater than or equal to 15, indicating that the month has at least 5 full weekends, and false otherwise.

Main Program:

• The program creates a list comprehension that iterates over all combinations of years from 1900 to 2100 and months from 1 to 12.
• For each combination, it calls the hasfiveweekend function to determine if the month in that year has at least 5 full weekends.
• The resulting list months contains tuples of years and months that meet this condition.

Output:

• The program prints the number of months with 5 full weekends.
• It prints the first five and last five months in the months list along with their corresponding years.

Extra Credit:

• The program extracts the unique years from the months list and calculates the number of years that do not have at least one month with 5 full weekends.
• It prints this number, representing the number of years within the specified range that do not contain any such month.

Overall, this code demonstrates how to use Julia to find months with a specific characteristic (5 full weekends) within a given year range and count related statistics.

isweekend(dt::Date) = Dates.dayofweek(dt) ∈ (Dates.Friday, Dates.Saturday, Dates.Sunday)

function hasfiveweekend(month::Integer, year::Integer)
    dmin = Date(year, month, 1)
    dmax = dmin + Dates.Day(Dates.daysinmonth(dmin) - 1)
    return count(isweekend, dmin:dmax) ≥ 15
end

months = collect((y, m) for y in 1900:2100, m in 1:12 if hasfiveweekend(m, y))

println("Number of months with 5 full-weekends: $(length(months))")
println("First five such months:")
for (y, m) in months[1:5] println(" - $y-$m") end
println("Last five such months:")
for (y, m) in months[end-4:end] println(" - $y-$m") end

# extra credit
yrs = getindex.(months, 1)
nyrs = 2100 - 1899 - length(unique(yrs))

println("Number of year with not one 5-full-weekend month: $nyrs")