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2021/13.js

@@ -0,0 +1,27 @@
+function day13(input, part2) {
+    input = input.split("\n").splitOnElement("")
+
+    let points = input[0].map((e) => new Point(...e.split(",").num())).pt
+    let instructions = input[1].map((e) => e.split(" ").last.split("=")).map((e) => [e[0], +e[1]])
+
+    for (let instruction of instructions) {
+        let pos = instruction[1]
+        let newPoints = [].pt
+
+        for (let point of points) {
+            if (instruction[0] == "x") {
+                newPoints.push(point.x < pos ? point : new Point(2 * pos - point.x, point.y))
+            } else {
+                newPoints.push(point.y < pos ? point : new Point(point.x, 2 * pos - point.y))
+            }
+        }
+
+        points = newPoints.uniq()
+
+        if (!part2) {
+            return points.length
+        }
+    }
+
+    return new Grid(points.max((e) => e.x).x + 1, points.max((e) => e.y).y + 1).mapMut((_, pt) => pt.isIn(points) ? "#" : " ").toString("")
+}