import Foundation
func findFridayThe13ths(startYear: Int, endYear: Int) {
for year in startYear...endYear {
for month in 1...12 {
if let date = Calendar.current.date(from: DateComponents(year: year, month: month, day: 13)) {
let weekday = Calendar.current.component(.weekday, from: date)
if weekday == 6 { // Friday in Swift's weekday system (Sunday = 1, Friday = 6)
print(String(format: "Friday the 13th: %d-%02d-13", year, month))
}
}
}
}
}
findFridayThe13ths(startYear: 2025, endYear: 2031)
/*
run:
Friday the 13th: 2025-06-13
Friday the 13th: 2026-02-13
Friday the 13th: 2026-03-13
Friday the 13th: 2026-11-13
Friday the 13th: 2027-08-13
Friday the 13th: 2028-10-13
Friday the 13th: 2029-04-13
Friday the 13th: 2029-07-13
Friday the 13th: 2030-09-13
Friday the 13th: 2030-12-13
Friday the 13th: 2031-06-13
*/
