Complete Dynamic Programming Practice - Noob to Expert | Topic Stream 1

Problemset link: https://codeforces.com/contestInvitation/dbdc3d98d7378b34a4a47114864882815a7669e9
Harmonic series blog: https://discuss.codechef.com/t/more-intuitive-explanation-for-the-harmonic-seriess-sum/67287

I end up covering problems A-H and K in the problemset.
Here's part 2, where I finish it: https://www.youtube.com/watch?v=kCY8seazgFU

Note that problem explanations are probably long because of interacting with chat, not necessarily because of difficulty. Also, sometimes I refer to the problemset as a "mashup" because Codeforces calls it that.

Timestamps:
Intro 00:00
Intro to DP (Fibonacci) 04:19
Mashup A 21:20
Mashup B 45:37
Trying to pin a message 52:05
Continuing B 56:25
Mashup C 1:08:49
Mashup D 1:30:45
Mashup E 1:46:22
Intermission (+ water bottle inspiration) 2:12:05
Mashup F 2:17:45
Figuring out what a derangement is 2:48:59
Mashup G 3:00:24
Mashup H 3:28:14
Mashup K 3:39:26