From 1afb266fa736b22eab5f7a1bd880d6a2fb6371e1 Mon Sep 17 00:00:00 2001
From: Seth Etter <sethetter@gmail.com>
Date: Tue, 5 Dec 2023 20:40:59 -0600
Subject: [PATCH] part 2, attempt 1 -- brute force, no bueno

---
 2023/day05/part2.ts | 68 +++++++++++++++++++++++++++++++++++++++++++--
 2023/day05/test.ts  | 44 ++++++++++++++++++++++++++---
 2 files changed, 106 insertions(+), 6 deletions(-)

diff --git a/2023/day05/part2.ts b/2023/day05/part2.ts
index 5658bc9..b3c7bb9 100644
--- a/2023/day05/part2.ts
+++ b/2023/day05/part2.ts
@@ -1,3 +1,5 @@
+import { assert } from "https://deno.land/std@0.208.0/assert/mod.ts";
+
 if (import.meta.main) {
   const input = (
     await Deno.readFile("input").then((bytes) =>
@@ -7,7 +9,69 @@ if (import.meta.main) {
   console.log(answer(input));
 }
 
+type Range = {
+  fromStart: number;
+  toStart: number;
+  range: number;
+};
+
+type MapRanges = {
+  from: string;
+  to: string;
+  ranges: Range[];
+};
+
 export function answer(input: string): number {
-  console.log(input);
-  return 42;
+  const [seedLine, _, ...mapLines] = input.split("\n");
+  const seedRanges = seedLine
+    .replace("seeds: ", "")
+    .split(" ")
+    .map((x) => parseInt(x));
+
+  const seeds = [];
+  for (let i = 0; i < seedRanges.length; i += 2) {
+    const from = seedRanges[i];
+    const to = from + seedRanges[i + 1];
+    for (let j = 0; j < to - from; j++) {
+      seeds.push(seedRanges[i] + j);
+    }
+  }
+
+  const mapRanges: MapRanges[] = mapLines
+    .join("\n")
+    .split("\n\n")
+    .map((mapLine) => {
+      const [fromToLine, ...rangeLines] = mapLine.split("\n");
+      const [_, from, to] = fromToLine.match(/([a-z]+)-to-([a-z]+) map/)!;
+      const ranges = rangeLines.map((rangeLine) => {
+        const [toStart, fromStart, range] = rangeLine
+          .split(" ")
+          .map((n) => parseInt(n));
+        return { fromStart, toStart, range };
+      });
+
+      return { from, to, ranges };
+    });
+
+  // start at `from: seed` to `to: location`
+  const locationNumbers = seeds.map((s) => getLocationNumber(s, mapRanges));
+
+  return Math.min(...locationNumbers);
+}
+
+function getLocationNumber(seed: number, mapRanges: MapRanges[]): number {
+  let current = "seed";
+  let currentNum = seed;
+  while (current !== "location") {
+    const mapRange = mapRanges.find(({ from }) => from === current);
+    assert(mapRange, `mapRange not found for: ${current}`);
+
+    const range = mapRange.ranges.find(
+      (r) => currentNum >= r.fromStart && currentNum <= r.fromStart + r.range,
+    );
+    if (range) currentNum = currentNum + (range.toStart - range.fromStart);
+
+    current = mapRange.to;
+  }
+  return currentNum;
 }
diff --git a/2023/day05/test.ts b/2023/day05/test.ts
index cc26a92..f2962d3 100644
--- a/2023/day05/test.ts
+++ b/2023/day05/test.ts
@@ -10,6 +10,7 @@ Deno.test("part1", () => {
     "50 98 2",
     "52 50 48",
     "",
+    // 13 + (15-0)
     "soil-to-fertilizer map:",
     "0 15 37",
     "37 52 2",
@@ -41,7 +42,42 @@ Deno.test("part1", () => {
   assertEquals(p1.answer(examples), 35);
 });
 
-// Deno.test("part2", () => {
-//   const examples = ["abc", "def"].join("\n");
-//   assertEquals(p2.answer(examples), 42);
-// });
+Deno.test("part2", () => {
+  const examples = [
+    "seeds: 79 14 55 13",
+    "",
+    "seed-to-soil map:",
+    "50 98 2",
+    "52 50 48",
+    "",
+    // 13 + (15-0)
+    "soil-to-fertilizer map:",
+    "0 15 37",
+    "37 52 2",
+    "39 0 15",
+    "",
+    "fertilizer-to-water map:",
+    "49 53 8",
+    "0 11 42",
+    "42 0 7",
+    "57 7 4",
+    "",
+    "water-to-light map:",
+    "88 18 7",
+    "18 25 70",
+    "",
+    "light-to-temperature map:",
+    "45 77 23",
+    "81 45 19",
+    "68 64 13",
+    "",
+    "temperature-to-humidity map:",
+    "0 69 1",
+    "1 0 69",
+    "",
+    "humidity-to-location map:",
+    "60 56 37",
+    "56 93 4",
+  ].join("\n");
+  assertEquals(p2.answer(examples), 46);
+});
-- 
2.51.2