2021.17

challenges/2021/17.js

@@ -0,0 +1,69 @@
+// Part 1
+const solvePuzzle1 = (input) => {
+  const [[minX, maxX], [minY, maxY]] = parseInput(input);
+
+  for (let x = 1; x <= maxX; x++) {
+    for (let y = -minY; y >= minY; y--) {
+      const foundHighestY = shoot(x, y, minX, maxX, minY, maxY);
+      if (foundHighestY) return foundHighestY;
+    }
+  }
+
+  return input;
+};
+
+// Part 2
+const solvePuzzle2 = (input) => {
+  const [[minX, maxX], [minY, maxY]] = parseInput(input);
+
+  let workedVelocityCount = 0;
+
+  for (let x = 1; x <= maxX; x++) {
+    for (let y = -minY; y >= minY; y--) {
+      workedVelocityCount += shoot(x, y, minX, maxX, minY, maxY) !== null ? 1 : 0;
+    }
+  }
+
+  return workedVelocityCount;
+};
+
+const shoot = (velX, velY, minX, maxX, minY, maxY) => {
+  let [x, y] = [0, 0];
+  let maxSeenY = 0;
+
+  while (x <= maxX && y >= minY) {
+    maxSeenY = Math.max(y, maxSeenY);
+
+    if (x >= minX && y <= maxY) return maxSeenY;
+
+    x += velX;
+    y += velY;
+
+    let velXChange = 0;
+
+    if (velX > 0) {
+      velXChange = -1;
+    } else if (velX < 0) {
+      velXChange = 1;
+    }
+
+    velX += velXChange;
+    velY -= 1;
+  }
+
+  return null;
+};
+
+const parseInput = (input) =>
+  input
+    .replace("target area: ", "")
+    .split(", ")
+    .map((l) =>
+      l
+        .slice(2)
+        .split("..")
+        .map((n) => Number(n))
+    );
+
+require(__dirname + "/../../utils/test.js").test(__filename, __dirname, solvePuzzle1);
+require(__dirname + "/../../utils/test.js").test(__filename, __dirname, solvePuzzle2);

challenges/2021/inputs/17.txt

@@ -0,0 +1 @@
+target area: x=241..273, y=-97..-63