From 35f5601f1e270885c886a0aad32135a63f8ad5a4 Mon Sep 17 00:00:00 2001
From: Lewis Dale <lewis.dale@triptease.com>
Date: Fri, 8 Dec 2023 08:24:48 +0000
Subject: [PATCH] Part One complete

---
 src/day_eight.ts | 98 ++++++++++--------------------------------------
 1 file changed, 19 insertions(+), 79 deletions(-)

diff --git a/src/day_eight.ts b/src/day_eight.ts
index 6743379..254029f 100644
--- a/src/day_eight.ts
+++ b/src/day_eight.ts
@@ -1,7 +1,6 @@
-import {anyCharOf, newline, rest, uniLetter, whitespace} from "parjs";
-import {then, many, manyTill, exactly, between, manySepBy, stringify} from "parjs/combinators";
+import {anyCharOf, newline, uniLetter, whitespace} from "parjs";
+import {between, exactly, manySepBy, manyTill, stringify, then} from "parjs/combinators";
 import fs from "fs";
-import {CamelCards} from "./day_seven";
 
 const patternParser = anyCharOf("LR").pipe(manyTill(newline().pipe(exactly(2))));
 
@@ -11,64 +10,16 @@ const nodeParser = nodeNameParser.pipe(then(childParser.pipe(between(" = ", whit
 
 const parser = patternParser.pipe(then(nodeParser.pipe(manySepBy(whitespace()))));
 
-class Node {
-	constructor(
-		public label: string,
-		public _left?: Node,
-		public _right?: Node
-	) {
-		if (this._left?.label === label) this._left = undefined;
-		if (this._right?.label === label) this._right = undefined;
-	}
-
-	public set left(node: Node) {
-		if (node.label !== this.label) {
-			this._left = node;
-		}
-	}
-
-	public set right(node: Node) {
-		if (node.label !== this.label) {
-			this._right = node;
-		}
-	}
-
-	public get left(): Node | undefined {
-		return this._left;
-	}
-
-	public get right(): Node | undefined {
-		return this._right;
-	}
-
-	public get isBranch(): boolean {
-		return Boolean(this.left || this.right);
-	}
-
-	/**
-	 * Find a node by label using basic Depth-first search
-	 */
-	public find(label: string, searchedNodes: string[] = []): Node | undefined {
-		if (this.label === label) return this;
-		if (searchedNodes.includes(this.label)) return;
-
-		if (this.left) {
-			const leftSearch = this.left.find(label, [...searchedNodes, this.label]);
-			if (leftSearch) return leftSearch;
-		}
-
-		if (this.right) {
-			const rightSearch = this.right.find(label, [...searchedNodes, this.label]);
-			if (rightSearch) return rightSearch;
-		}
-	}
-}
+type Maybe<T> = T | undefined;
 
 type Instruction = "L" | "R";
+type NodeName = string;
+type NodeChildren = [Maybe<NodeName>, Maybe<NodeName>];
 
 export class DesertMap {
 	private readonly pattern: Instruction[];
-	private tree?: Node;
+
+	private map: Record<NodeName, NodeChildren> = {};
 
 	constructor(input: string) {
 		const [pattern, nodes] = parser.parse(input).value;
@@ -76,38 +27,27 @@ export class DesertMap {
 		this.pattern = pattern as Instruction[];
 
 		for (const [name, [[leftNode, rightNode]]] of nodes) {
-			if (!this.tree) {
-				this.tree = new Node(name);
-			}
-
-			const parent = this.tree.find(name);
-
-			if (!parent) {
-				console.log(`No parent found for label ${name}`)
-			} else {
-
-				const foundLeft = this.tree.find(leftNode);
-				parent.left = foundLeft || new Node(leftNode);
-
-				const foundRight = this.tree.find(rightNode);
-				parent.right = foundRight || new Node(rightNode);
+			if (!this.map[name]) {
+				this.map[name] = [undefined, undefined];
 			}
+			const children = [leftNode !== name ? leftNode : undefined, rightNode !== name ? rightNode : undefined];
+			this.map[name] = children as NodeChildren;
 		}
 	}
 
 	public stepsTo(node: string): number {
-		if (!this.tree) return 0;
-
 		let step = 0;
-		let curr = this.tree;
+		let curr = "AAA";
 
-		while (curr.label !== node) {
+		while (curr !== node) {
 			const instruction = this.pattern[step % this.pattern.length];
 
-			if (instruction === "L" && curr.left) {
-				curr = curr.left;
-			} else if (instruction === "R" && curr.right) {
-				curr = curr.right;
+			const [left, right] = this.map[curr];
+
+			if (instruction === "L" && left) {
+				curr = left;
+			} else if (instruction === "R" && right) {
+				curr = right;
 			}
 
 			if (!curr) return 0;