21/06/24 19:39:02.06 XMpTcDaC.net
>>21 Ruby
y = 2021
w = Time.new( y ).wday
tbl = ( (y & 3) == 0 && (y % 100) != 0 || (y % 400) == 0 )?
[ [25,23,25,24,25,24,25,25,24,25,24,25], [2,1,5,3,0,5,2,6,4,1,6,3] ] :
[ [25,22,25,24,25,24,25,25,24,25,24,25], [2,2,6,4,1,6,3,0,5,2,0,4] ]
12.times{|m|
puts "%04d-%02d-%02d" % [ y, m+1, tbl[0][m] + ((tbl[1][m]-w) % 7) ]
}