feat(day-4): add part 2 solution

1 files changed, 10 insertions, 3 deletions

diff --git a/day-4/script.ts b/day-4/script.ts
index 53488b5..cb2f643 100644
--- a/day-4/script.ts
+++ b/day-4/script.ts
@@ -14,17 +14,24 @@ function parseNumbers(s: string) {
   return chunks(s.split(""), 3).map((chunk) => Number(chunk.join("")));
 }
 
-const result = fs
+const lines = fs
   .readFileSync("./input.txt")
   .toString()
   .split("\n")
-  .slice(0, -1)
+  .slice(0, -1);
+
+const result = lines
   .map((line) => {
     const [_cardStr, dataStr] = line.split(": ");
     const [winning, existing] = dataStr.split("| ").map(parseNumbers);
     return { winning, existing };
   })
   .map((data) => data.existing.filter((x) => data.winning.includes(x)).length)
-  .reduce((acc, winCount) => acc + (winCount ? 2 ** (winCount - 1) : 0), 0);
+  .reduce((acc, winCount, index) => {
+    return acc.map((v, i) =>
+      i > index && i <= index + winCount ? v + acc[index] : v,
+    );
+  }, new Array(lines.length).fill(1))
+  .reduce((acc, v) => acc + v, 0);
 
 console.log({ result });