find - find -cmin 0 和 -ctime 0 的规则

Question

我正在研究 command find，我看到：

-cmin n
              File's status was last changed n minutes ago.
-ctime n
              File's status was last changed n*24 hours ago.

但是当n为零时，差异就来了，这种行为是否有合理的解释？

$ date
Thu 23 Jul 2020 02:16:17 PM CST
$ 
$ touch a 
$ find -name a -cmin 0
$ find -name a -cmin 1
./a
$ find -name a -ctime 0
./a
$ find -name a -ctime 1
$ 
$ date
Thu 23 Jul 2020 02:16:18 PM CST
$