day 6 complete!

day05/js/day05b.js

@@ -0,0 +1,94 @@
+import { promises as fsPromises } from "node:fs";
+
+async function asyncReadFile(filename) {
+    try {
+        const contents = await fsPromises.readFile(filename, "utf-8");
+
+        const arr = contents.split(/\r?\n/);
+
+        return arr;
+    } catch (err) {
+        console.error(err);
+    }
+}
+
+const countRanges = (ranges) => {
+    console.log({ ranges });
+    let newRanges = [...ranges];
+    let overlapCount = -1;
+
+    while (overlapCount !== 0) {
+        overlapCount = 0;
+        newRanges = newRanges.reduce((acc, curr) => {
+            let hasOverlap = false;
+            const [currStart, currEnd] = curr.split("-").map((val) => val * 1);
+            acc = (acc ?? []).map((range) => {
+                const [start, end] = range.split("-").map((val) => val * 1);
+
+                // exclude ones either before or after range
+                if (currStart > end || currEnd < start) return range;
+
+                // that means that it must overlap
+                hasOverlap = true;
+                return `${Math.min(currStart, start)}-${Math.max(
+                    currEnd,
+                    end
+                )}`;
+            });
+
+            if (hasOverlap) overlapCount++;
+            else acc.push(curr);
+
+            return acc;
+        }, []);
+    }
+
+    console.log({ newRanges });
+    return newRanges.reduce((total, curr) => {
+        const [currStart, currEnd] = curr.split("-").map((val) => val * 1);
+        console.log(`adding ${1 + currEnd - currStart}`);
+        return total + 1 + currEnd - currStart; // +1 because it's inclusive of the end
+    }, 0);
+};
+
+const parseData = (rows) => {
+    let isInRanges = true;
+    let freshRanges = [];
+    let freshCount = 0;
+
+    rows.forEach((row) => {
+        if (isInRanges) {
+            if (row === "") {
+                isInRanges = false;
+                return;
+            }
+
+            if (row.includes("-")) {
+                freshRanges.push(row);
+                return;
+            }
+
+            return;
+        }
+    });
+
+    return countRanges(freshRanges);
+};
+
+const testData = `
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32
+`.trim();
+
+const rows = await asyncReadFile("../input.txt");
+
+console.log(`Fresh ingredient count: ${parseData(rows)}`);

day05/notes.md

@@ -4,9 +4,12 @@ Puzzle 1 took me 30-ish minutes to figure out. I initially tried building an arr
 
 Puzzle 2 seemed pretty straightforward, and I thought I had a simple solution, but it didn't work, and an hour later (1:30a), I have to admit defeat for tonight.
 
+_UPDATE:_ I came back to it the next night and realized what I was doing wrong - my algorithm was both overspecified and incomplete. The fix was to simplify things, exclude ranges that don't overlap, and then merge any that do. Another 15 minutes and it was solved.
+
 ### JS Solutions
 
 ```
 cd js
 node day05a.js
+node day05b.js
 ```