They are published on the leetcode website. Here's a screenshot showing where to click [1].

LeetCode does have an "unofficial" API to get the problem of the day. Should work for previous days as well. This code worked last I tried [2].

[1] https://github.com/ebanner/daily-coding-challenges#leetcode

[2] https://github.com/ebanner/get-daily-leetcode-problem/blob/m...