Online coding summer camp in Germany, 2027

from datetime import date, timedelta

# KMK summer holidays 2027, first and last holiday day (Sommerferienregelung 2025 to 2030)
summer = {
    "Baden-Württemberg": ("29.07.", "11.09."), "Bayern": ("02.08.", "13.09."),
    "Berlin": ("01.07.", "14.08."), "Brandenburg": ("01.07.", "14.08."),
    "Bremen": ("08.07.", "18.08."), "Hamburg": ("01.07.", "11.08."),
    "Hessen": ("28.06.", "06.08."), "Mecklenburg-Vorpommern": ("05.07.", "14.08."),
    "Niedersachsen": ("08.07.", "18.08."), "Nordrhein-Westfalen": ("19.07.", "31.08."),
    "Rheinland-Pfalz": ("28.06.", "06.08."), "Saarland": ("28.06.", "06.08."),
    "Sachsen": ("10.07.", "20.08."), "Sachsen-Anhalt": ("10.07.", "20.08."),
    "Schleswig-Holstein": ("03.07.", "14.08."), "Thüringen": ("10.07.", "20.08."),
}

def day(text):
    d, m = text.strip(".").split(".")
    return date(2027, int(m), int(d))

# step 1: Länder with the same dates can share one camp plan
groups = {}
for land, (first, last) in summer.items():
    groups.setdefault((day(first), day(last)), []).append(land)
print("Different summer holidays:", len(groups))

# a quick first try: holiday days divided by 7
for (first, last), lands in sorted(groups.items()):
    days = (last - first).days + 1
    print(", ".join(lands), "|", days, "days |", days // 7, "weeks")

It prints Different summer holidays: 10, then one line per group, for example Hessen, Rheinland-Pfalz, Saarland | 40 days | 5 weeks, Hamburg | 42 days | 6 weeks and Bremen, Niedersachsen | 42 days | 6 weeks.

# step 2: count the whole Monday to Friday weeks inside each holiday
for (first, last), lands in sorted(groups.items()):
    monday = first + timedelta(days=(7 - first.weekday()) % 7)
    weeks = []
    while monday + timedelta(days=4) <= last:
        weeks.append(monday)
        monday += timedelta(days=7)
    print(first.strftime("%d %b"), "to", last.strftime("%d %b"), "|", len(weeks), "camp weeks, first",
          weeks[0].strftime("%d %b"), "|", ", ".join(lands))

Run after Version 1. It prints, among others, 01 Jul to 11 Aug | 5 camp weeks, first 05 Jul | Hamburg, 28 Jun to 06 Aug | 6 camp weeks, first 28 Jun | Hessen, Rheinland-Pfalz, Saarland and 08 Jul to 18 Aug | 5 camp weeks, first 12 Jul | Bremen, Niedersachsen.