def weekday_by_zeller(y,m,d) y -= 1 if m == 1 or m == 2 m += 12 if m == 1 or m == 2 h = y + (y/4).floor - (y/100).floor + (y/400).floor + ((13*m+8)/5).floor + d return "sun" if h % 7 == 0 return "mon" if h % 7 == 1 return "tue" if h % 7 ==…