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https://github.com/csauve/bookworm

A BattleSnake bot for 2020
https://github.com/csauve/bookworm

battlesnake rust

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A BattleSnake bot for 2020

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README 

        
# Bookworm 🐛



Bookworm is a [BattleSnake][1] bot written in [Rust][2] for the March 2020 tournament. Combines the strategies of pruned turn tree exploration, minimax, and heuristic scoring. The snake is given a time budget to explore the turn tree; the fewer the snakes, the deeper the exploration.



![](screenshot.png)

_A server instance playing against itself using the built-in host mode. See `play-host.sh` as an example._



## Building and running



Just run `cargo build --release` to produce a self-contained binary at `target/release/bookworm`. The binary can be invoked with a number of modes and options, which the `-h` flag explains in detail. The available modes are:



* **server:** Runs as a typical snake API server, ready to be play.

* **host:** Locally hosts a match between given snakes, logging each turn state. Implements 2020 rules.

* **benchmark:** A series of common operations are timed and logged.



## Development



Unit tests can be run with `cargo test`, though some strategy tests will fail currently. To quickly build and run the bot, use `cargo run `. Note that the development build is significantly slower at runtime than the release build, so you may need to increase the `--timeout` for host mode and give the server more time budget with `--budget` to achieve similar lookahead depths.



### Todos and improvement ideas:

* Heuristics and strategy

  * Implement more unit tests for behaviour

  * Seed the turn tree exploration with some longer term "plays" instead of just single space movements

  * Allow for chances of death instead of assumed worst case

  * If death unavoidable, prefer head-to-head

  * Are there heuristic elements we can skip sometimes?

* Performance

  * Can I write some `const fn` to move work to compile time?

  * Can I use fixed arrays or `vec![0.0; src.len()]` anywhere?

  * Look for places to use `.copied()` instead of `.cloned()`

  * Avoid indexing into vecs; use `if let Some(x) = vec.get(i)`

  * [infallible DS][3] to avoid empty checks

  * Move hosting to `us-west-1` to be closer to BS host

* Pathfinding (if used)

  * JPS

  * Dynamic heuristic weight



### The "wat" list



Questionable life choices:



* [Turn 114: Feeding rule change?](https://play.battlesnake.com/g/72eee8c6-7b26-4b81-afb0-1afa17f5c5bf/)

* [Turn 230: Gave enemy opportunity to easily kill us head-to-head](https://play.battlesnake.com/g/04c853c2-0e3e-4013-8bb5-fd66a82ce2d6/)

* [Turn 383: Gave enemy opportunity to easily trap us](https://play.battlesnake.com/g/c196792b-7a8c-4ccf-b63d-d89da1fdba6b/)

* [Turn 300: Trapped self... why??](https://play.battlesnake.com/g/880a59ac-3fe9-4204-a37c-6cbf796f5030/)

* [Turn 36: Giving up too early](https://play.battlesnake.com/g/a1646958-edda-4000-9fde-a926292ba1d0/)

* [Turn 13: Allow for chance of survival](https://play.battlesnake.com/g/53b159ea-a914-493d-8c73-54680186fafa/)

* [Turn 21: Prefer going up because less likely blue_bottle will go there](https://play.battlesnake.com/g/eff9c73e-cbb2-4bf9-98a1-89f0e8244bcb/)

* [Turn 74: Ran into another snake, but should prefer possibility of head-to-head death](https://play.battlesnake.com/g/977be8a8-ca65-48b8-bc8c-37310ab61701/)

* [Turn 240: Could have trapped enemy but didn't](https://play.battlesnake.com/g/639eb325-932a-463c-9f4c-5aaa96495f7d/)

* [Turn 122: Ditto above](https://play.battlesnake.com/g/23b1ec46-6c97-407a-b6a7-9aee9b75464d/)

* [Turn 15: Didn't understand stacked tail rule?](https://play.battlesnake.com/g/93a1babe-2aa6-411f-b67d-e20e4d6d644c/)



## References and resources



* https://github.com/BattlesnakeOfficial/rules/blob/master/standard.go

* https://github.com/BattlesnakeOfficial/engine/blob/master/rules/tick.go

* https://github.com/anvaka/ngraph.path

* https://github.com/riscy/a_star_on_grids

* https://www.redblobgames.com/pathfinding/grids/algorithms.html

* [http://likebike.com/posts/How_To_Write_Fast_Rust_Code.html][3]



[1]: https://play.battlesnake.com/

[2]: https://www.rust-lang.org/

[3]: http://likebike.com/posts/How_To_Write_Fast_Rust_Code.html