Stateful Solvers and Iterators

2022-10-16

Rust, yet again! Let’s take what we did last time with Solving Sudoku (again) and improve the code structure a bit more.

Goals:

Create a ‘Solver’ struct that can maintain state (such as how many states we’ve visited, how much time we’ve spent)
Track the above stats
Turn the ‘Solver’ into an iterator which will iterate through given solutions (a single call will give the first solution or you can run through the iterator to get all of them)

If you’d like to follow along, I’ve started uploading the code here: https://github.com/jpverkamp/rust-solvers

Solving Sudoku (again)

2022-10-04

More Rust! This time, I want to go back to my post on A Generic Brute Force Backtracking Solver. For one, because I’m learning Rust. For two, because there is a crate specifically for im mutable data structures. And for three, because I expect it will be much faster. We shall see!

AoC 2021 Day 23: Amphipodinator

2021-12-23

Source: Amphipod

Part 1: Given 4 rooms full of amphipods with various energy costs for movement (a=1, b=10, c=100, d=1000) and a hallway, how much energy does it take (at minimum) to sort the amphipods into their own rooms with the following conditions:

AoC 2021 Day 22: Cubinator

2021-12-22

Source: Reactor Reboot

Part 1: Given a series of 3D cubes that either turn ON all or turn OFF all points in their region, calculate how many points in the region (-50..50,-50..50,-50..50) are ON at the end.

AoC 2021 Day 21: Dicinator

2021-12-21

Source: Dirac Dice

Part 1: Play a simple game (describe below) with a loaded D100 (that always rolls 1, 2, 3, … 99, 100, 1, …). Return the score of the losing player times the number of times the die was rolled.

AoC 2021 Day 15: Low Ceiling Simulator

2021-12-15

Source: Chiton

Part 1: Given a grid of weights, find the minimum path from top left to top right. Return the total weight along that path.

AoC 2021 Day 12: Submarine Spider

2021-12-12

Source: Passage Pathing

Part 1: Given a list of edges in a bi-directional graph, count the number of paths from `start` to `end` such that nodes named with lowercase letters are visited once, and nodes with uppercase letters can be visited any number of times.

AoC 2021 Day 8: Seven Segment Demystifier

2021-12-08

Source: Seven Segment Search

Part 1: Simulate a seven segment displey where you do not know which input wire controls which segment. Given the wires used in all ten digits and four output digits, count how many times 1, 4, 7, and 8 are outputted.

Solving Snakebird

2021-08-18

Snakebird!

A cute little puzzle game, where you move around snake(birds). Move any number of snakes around the level, eating fruit, and getting to the exit. The main gotchas are that you have gravity to content with–your snake will easily fall off the edge of the world–and each time you eat a fruit, your snake gets bigger. This can help get longer to get into hard to reach places or it can cause trouble when you trap yourself in corners.

Let’s use the new immutable.js solver to solve these problems!

Immutable.js Solvers

2021-08-17

A bit ago I wrote about writing a generic brute force solver (wow, was that really two months ago?). It got … complicate. Mostly, because every time I wrote a step function, I had to be careful to undo the same. Wouldn’t it be nice if we could just write a step function and get backtracking for ‘free’?

Well, with immutability you can!

Source: Amphipod

Part 1: Given 4 rooms full of amphipods with various energy costs for movement (a=1, b=10, c=100, d=1000) and a hallway, how much energy does it take (at minimum) to sort the amphipods into their own rooms with the following conditions:

Source: Reactor Reboot

Part 1: Given a series of 3D cubes that either turn ON all or turn OFF all points in their region, calculate how many points in the region (-50..50,-50..50,-50..50) are ON at the end.

Source: Dirac Dice

Part 1: Play a simple game (describe below) with a loaded D100 (that always rolls 1, 2, 3, … 99, 100, 1, …). Return the score of the losing player times the number of times the die was rolled.

Source: Chiton

Part 1: Given a grid of weights, find the minimum path from top left to top right. Return the total weight along that path.

Source: Passage Pathing

Part 1: Given a list of edges in a bi-directional graph, count the number of paths from start to end such that nodes named with lowercase letters are visited once, and nodes with uppercase letters can be visited any number of times.

Source: Seven Segment Search

Part 1: Simulate a seven segment displey where you do not know which input wire controls which segment. Given the wires used in all ten digits and four output digits, count how many times 1, 4, 7, and 8 are outputted.

Part 1: Given a list of edges in a bi-directional graph, count the number of paths from `start` to `end` such that nodes named with lowercase letters are visited once, and nodes with uppercase letters can be visited any number of times.