1 files changed, 49 insertions, 0 deletions
diff --git a/2021/13/solve.js b/2021/13/solve.js
new file mode 100644
index 0000000..d8c2d3c
--- /dev/null
+++ b/2021/13/solve.js
@@ -0,0 +1,49 @@
+const { _, performance } = require("perf_hooks");
+const fs = require("fs");
+
+const [dot_data, fold_data] = fs.readFileSync("input", "utf8").split("\n\n");
+
+// Why doesn't JS have Tuples?!
+class Tupility extends Set {
+    add = (elem) =>
+        super.add(typeof elem === "object" ? JSON.stringify(elem) : elem);
+    iterable = () => [...this].map(JSON.parse);
+}
+
+function solve() {
+    let dots = new Tupility();
+    dot_data.split("\n").forEach((line) => {
+        const [x, y] = line.split(",").map(Number);
+        dots.add([x, y]);
+    });
+
+    let first = 0;
+    fold_data.split("\n").forEach((line) => {
+        let [dir, amount] = line.substr(11).split("=");
+        if (!dir) return;
+        amount = +amount;
+        const changed = new Tupility();
+        dots.iterable().forEach(([x, y]) =>
+            changed.add([
+                dir == "x" && x >= amount ? 2 * amount - x : x,
+                dir == "y" && y >= amount ? 2 * amount - y : y,
+            ])
+        );
+        dots = changed;
+        if (!first) first = dots.size;
+    });
+
+    // ANSI escape sequences
+    let out = process.stdout;
+    out.write("\u001b[2J");
+    dots.iterable().forEach(([x, y]) =>
+        out.write("\u001b[" + (y + 1) + ";" + x + "H█")
+    );
+
+    console.log("\n\n" + first);
+}
+
+const tic = performance.now();
+solve();
+const toc = performance.now();
+console.log("TIME: " + ((toc - tic) / 1000).toFixed(6) + " seconds");