day 15 part 2

NullDev · Dec 15, 2024 · b30b248 · b30b248
1 parent 06a325f
commit b30b248
Showing 1 changed file with 56 additions and 6 deletions.
diff --git a/2024/Day_15/part_2.js b/2024/Day_15/part_2.js
@@ -8,16 +8,66 @@ const __dirname = path.dirname(fileURLToPath(import.meta.url));
 // = Copyright (c) NullDev = //
 // ========================= //
 
-const INPUT = String(fs.readFileSync(path.join(__dirname, "input.txt"))).trim().split("\n");
+/* eslint-disable no-param-reassign, no-nested-ternary, one-var, consistent-return */
+
+const INPUT = String(fs.readFileSync(path.join(__dirname, "input.txt"))).trim().split("\n\n");
 
 const pStart = performance.now();
 
-//
-// YOUR CODE HERE
-//
-const result = "...";
+// honestly too lazy to come up with a short functional approach...
+
+const res = (([fir, sec]) => {
+    const dmap = new Map([["v", [1, 0]], [">", [0, 1]], ["^", [-1, 0]], ["<", [0, -1]]]);
+    const arr = fir.split("\n");
+    sec = sec.split("\n").join("");
+
+    const narr = arr.map(row => row.split("").reduce((acc, ch) =>
+        acc + (ch === "O" ? "[]" : ch === "@" ? "@." : ch + ch), ""),
+    ).map(r=>r.split(""));
+
+    let r, c;
+    narr.forEach((row, i) => row.forEach((v, j) => ((v === "@") && (r = i) && (c = j) && (narr[i][j] = "."))));
+
+    const dfs = (rr, cc, dr, boxes) => {
+        if(narr[rr][cc] === "#") return false;
+        if(narr[rr][cc] === ".") return true;
+        const nr = rr + dr, nc = cc;
+        if (boxes.has(nr + "," + nc)) return true;
+        boxes.add(nr + "," + nc);
+        if (!dfs(nr, nc, dr, boxes)) return false;
+        return narr[rr][cc] === "[" ? dfs(rr, cc + 1, dr, boxes) : dfs(rr, cc - 1, dr, boxes);
+    };
+
+    [...sec].forEach(ch => { // @ts-ignore
+        const [dr, dc] = dmap.get(ch);
+        const nr = r + dr, nc = c + dc;
+        if (narr[nr][nc] === "#") return;
+        if (narr[nr][nc] === ".") return (r = nr) && (c = nc);
+        if (ch === "<" || ch === ">"){
+            const cr = nr;
+            let cc = nc;
+            while (narr[cr][cc] === "[" || narr[cr][cc] === "]") cc += dc;
+            if (narr[cr][cc] !== ".") return;
+            while (cr !== nr || cc !== nc) (narr[cr][cc] = narr[cr - dr][cc - dc]) && (cc -= dc);
+            (narr[cr][cc] = ".") && (c = nc);
+        }
+        else {
+            const boxes = new Set();
+            if (!dfs(nr, nc, dr, boxes)) return;
+            const barr = [...boxes].map(a=>a.split(",").map(Number))
+                .sort((a, b)=>ch === "^" ? a[0] - b[0] : b[0] - a[0]); // @ts-ignore
+            (barr.forEach((
+                [rb, cb], _, __, pr = rb - dr, pc = cb,
+            ) => ((narr[rb][cb] = narr[pr][pc]) && (narr[pr][pc] = "."))) || 1) && (r = nr);
+        }
+    });
+
+    return narr.reduce((sum, row, r1) =>
+        sum + row.reduce((s, v, c1) => s + (v === "[" ? r1 * 100 + c1 : 0), 0), 0,
+    );
+})(INPUT);
 
 const pEnd = performance.now();
 
-console.log("<DESCRIPTION>: " + result);
+console.log("FINAL SUM OF COORDINATES: " + res);
 console.log(pEnd - pStart);