Reading times in R, if the format varies

I have a file from the Canadian Hydrographic service that writes times as '%Y-%m-%d' if it's the first second of a day, but as '%Y-%m-%d %H:%M:%s' otherwise. This video shows how to deal with that. (Spoiler alert: the standard R functions `as.POSIXct()` and `as.POSIXlt()` need a hint!)