Gacha prob and mechanism is not correct

[WetABQ]

Gacha prob has prob increasing mechanism and stable mechanism

and UP gacha pool does not contain Amber, Kaeya, and Lisa

4 star UP also has the pity mechanism.

We could refer to this passage (Chinese)
And I also once wrote a QQ bot Gacha Emulator with an overall customize pipeline system for it, you could refer this code (write in Kotlin)

Pity & UP

Stable Mechanism

Overall Pipeline

[WetABQ]

I will translate it later ;)

[lunaticwhat]

since gacha algorithm is still a PoC and hardcoded in some way, we still need to improve it with better math !

[Jirehlov]

I'd recommend the same algorithm as well.
For more reference only,
PoC in C++: https://github.com/Jirehlov/libgiwscli
PoC in Python: https://github.com/CMHopeSunshine/Genshin_Gacha_XY

Also some tips,

1. The counters in the "Stable Mechanism" should be cleared once the current banner ends;
2. Mersenne Twister is recommended;
3. Expected probs are,
   for weapon banners,
   5-star items overall prob: 1.87793%
   4-star items overall prob: 14.8412%
   for char banners and Permanent Wish,
   5-star items overall prob: 1.60521%
   4-star items overall prob: 13.0566%