## Saturday, 26 May 2018

### DDR, the 4th year

Some references:
[5/2016] DDR the 2nd year
[2/2017] DDR the 3rd year

Oh my. Just take a look at the screenshots in the above entries and look at the scores that I have now...

ちくわパフェだよ☆CKP Challenge Lv14
2016 - 881970 1 miss [That's really a fluke - I can't even consistently 4 miss Lv14 maps]
2017 - 918640 1 miss [That's more like regular performance]
2018 - 938370 GFC [without proper warm up so that's an underperformed play]

MAX300 Expert Lv15
2016 - ~890000 (ITG converted into DDR A scale) [again fluked somehow]
2018 - 912380 [not like I seriously grinded since I play 12-14-16+ these days... didn't even bothered to screenshot that]

2017 - 557020 Failed [Can't even make it to the laddery stream part]
2018 - 833420 [I think I'm hitting that stream too fast nowdays]

2017 - 780660 [After playing BPM200 for a whole day]
2018 - 884020 [Playing BPM200 is almost natural for me now]

Oh and of course, I can barely handle some 18s now.

Great improvement comes from consistent targeted practicing just like what happened in 2016. In 2 months I improved from being able to marginally pass 16s to clearing some of the nastiest 17 [Tohoku Evolved, Spanish Snowy Dance] and even some 18s [Egoism, Mei, and almost Dead End Groove Radar mix].

I think that comes from a general theory that I believe to be true in explosiveness demanding sports: strength comes first and accuracy follows. Strength and accuracy is the eternal dilemma in sporting and improving one will inevitably sacrifice another expert for those chosen geniuses. Now you are an ordinary player and you have to decide which is more important to be focused and I will definitely go for strength.

Since we are not talking about pure fitness that puts excessive muscles into no use, we can generally say that greater strength allows stronger explosiveness and hence a larger margin for flexibility. That means you can sacrifice your strength [speed] to gain higher accuracy [firmer stepping that gives higher accuracy]. And more importantly you have the stamina to keep your performance and strength to fix your mistakes whenever necessary. It does not work the other way round however. Stamina and strength is the correcting factor while you do not get either if you focused on accuracy only.

It's not surprising to find players who can often pass 15-16s focused on steamrolling 12s regularly and never gain the ability to clear high 16 or 17s. Strength based players however, managed to raise their accuracy naturally by adopting their ways of advanced maps onto easier maps that are more stable and more easily corrected. Wind Fairy is a good example: it's a very simple Lv15 but with some serious 1/3 streams. There's even a vertical stream at the last which is extremely hard for Lv15 newcomers. Higher players however, can apply the dense jumping skill they gained by playing maps like MAX period or London Evolved [I hate this thing so much] so get it passed.

This theory is general in the sense that it applies to more sports other than DDR - and baseball is my favourite example. While weaker CPBL pitchers are still trying to pitch slower in order to pitch into the zone, MLB is exhibiting why the other way round is the correct way to grow a prospect: throw hard, throw fast. That's your true potential and you should try your best to grind the best out of it.

So that's my little thoughts on how to get better when you play these games/sports. I'm not saying that keep on AAA 12s are bad, nor that people have to do it in that way to be good. There are all different kinds of players in the world and there are millions of optimized way to improve the skills -- but I will keep my way playing DDR while enjoying all the songs you get there.

Statistics, mid 2018:
409 credits accumulated since DDR A
20 credits per week
Clear attack: 14~15-[2016] → 15+~16[2017] → 17~18-[2018]
AA Attack: 11~13-[2016] → 14~15-[2017] → 15~16[2018]
Lv 16: 29 Cleared / 4AA
Lv 17: 25 Cleared / 10A
Lv 18: 3 Cleared

## Tuesday, 22 May 2018

### 10 years of Osu! 雜談(2) - pp篇

$p = P(|Z|\leq \theta _{300}/\sigma )$

$q = P(|Z|\leq \theta _{100}/\sigma )$

$\theta_{300} = 31.5, \theta_{100} = 75.5, n=500$

$LR(\sigma) = \frac{p}{500(q-p)} = 1 \Rightarrow \frac{p}{q} = \frac{500}{501}$

$P(r\times 100, 1\leq r\leq k) = \sum _{r=1}^k C^n_rp^{n-r} q^r \approx \sum n^r p^{n-r}q^r = p^{n-1}n(q-p)\frac{p^k-n^k(q-p)^k}{p^k-np^{k-1}(q-p)}$

$LR(\sigma) = \frac{p}{n(q-p)}\frac{p^k-np^{k-1}(q-p)}{p^k-n^k(q-p)^k}$

$n^{k+1}(q-p)^{k+1} -2np^k (q-p)+p^{k+1} = 0$

$f(x) = n^{k+1}(1-x)^{k+1}-2nx^k(1-x)+x^{k+1} = 0$

$f(\frac{n}{n+1}) = n^{k+1}(\frac{1}{n+1})^{k+1} -2n(\frac{n}{n+1})^{k}(\frac{1}{n+1}) + (\frac{n}{n+1})^{k+1} = 0$

$f(\frac{2n}{2n+1})=(\frac{n}{2n+1})^{k+1}-2n(\frac{2n}{2n+1})^{k}(\frac{1}{2n+1}) + (\frac{2n}{2n+1})^{k+1} < 2^{-k-1} \to 0$

$\sigma = (\theta _{300} - 0.4)(\log (dn+1))^{-0.605}$

TL;DR SS所給予的PP獎勵在連續性和數據上毫無意義，夠準的話SS就自然會出來 佛系SS

wmfchris
21/5/2018 [剛好十年又兩個月]