Easter date gauss algorithm

other/gauss_easter.py

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+"""
+https://en.wikipedia.org/wiki/Computus#Gauss'_Easter_algorithm
+"""
+import math
+from datetime import datetime, timedelta
+
+
+def gauss_easter(year: int) -> datetime:
+    """
+    Calculation Gregorian easter date for given year
+
+    >>> gauss_easter(2007)
+    datetime.datetime(2007, 4, 8, 0, 0)
+
+    >>> gauss_easter(2008)
+    datetime.datetime(2008, 3, 23, 0, 0)
+
+    >>> gauss_easter(2020)
+    datetime.datetime(2020, 4, 12, 0, 0)
+
+    >>> gauss_easter(2021)
+    datetime.datetime(2021, 4, 4, 0, 0)
+    """
+    a = year % 19
+    b = year % 4
+    c = year % 7
+    k = math.floor(year / 100)
+    p = math.floor((13 + 8 * k) / 25)
+    q = k / 4
+    M = (15 - p + k - q) % 30
+    N = (4 + k - q) % 7
+    d = (19 * a + M) % 30
+    e = (2 * b + 4 * c + 6 * d + N) % 7
+
+    if d == 29 and e == 6:
+        return datetime(year, 4, 19)
+    elif d == 28 and e == 6:
+        return datetime(year, 4, 18)
+    else:
+        return datetime(year, 3, 22) + timedelta(days=int(d + e))
+
+
+if __name__ == '__main__':
+    print(f"Easter in 2023 will be {gauss_easter(2023)}")
+    print(f"Easter in 2021 will be {gauss_easter(2021)}")
+    print(f"Easter in 2010 was {gauss_easter(2010)}")
+    print(f"Easter in 1994 was {gauss_easter(1994)}")
+    print(f"Easter in 2000 was {gauss_easter(2000)}")