Solve 2020/17

2020/17/example

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+.#.
+..#
+###

2020/17/input

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+#...#...
+#..#...#
+..###..#
+.#..##..
+####...#
+######..
+...#..#.
+##.#.#.#

2020/17/solution1.js

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+const fs = require("fs");
+
+const input = fs.readFileSync("input", "utf-8").trim();
+const startPlane = input.split("\n").map((line) => line.split(""));
+
+let pocket = [startPlane];
+
+function main() {
+  for (let step = 1; step <= 6; step++) {
+    const countActive = cycle();
+    console.log(`After ${step} steps: ${countActive}`);
+    if (step === 1 || step === 2) {
+      printPocket();
+    }
+  }
+}
+
+function cycle() {
+  let squareLength = pocket[0].length;
+  let countActive = 0;
+  const nextPocket = [];
+  for (let z = -1; z < pocket.length + 1; z++) {
+    const plane = [];
+    for (let x = -1; x < squareLength + 1; x++) {
+      const line = [];
+      for (let y = -1; y < squareLength + 1; y++) {
+        const nextState = getState(z, x, y);
+        if (nextState === "#") countActive++;
+        line.push(nextState);
+      }
+      plane.push(line);
+    }
+    nextPocket.push(plane);
+  }
+  pocket = nextPocket;
+
+  return countActive;
+}
+
+function getState(pz, px, py) {
+  let activeNeighbors = 0;
+  for (const z of range(pz - 1, pz + 2)) {
+    for (const x of range(px - 1, px + 2)) {
+      for (const y of range(py - 1, py + 2)) {
+        if (pz === z && px === x && py === y) continue;
+        if (isActive(z, x, y)) activeNeighbors++;
+      }
+    }
+  }
+  // console.log(`${py},${px},${py}: ${activeNeighbors}`);
+  if (isActive(pz, px, py)) {
+    return activeNeighbors === 2 || activeNeighbors === 3 ? "#" : ".";
+  } else {
+    return activeNeighbors === 3 ? "#" : ".";
+  }
+}
+
+function isActive(z, x, y) {
+  return pocket[z]?.[x]?.[y] === "#";
+}
+
+function range(start, stop, increment = 1) {
+  if (typeof stop === "undefined") {
+    stop = start;
+    start = 0;
+  }
+  const r = [];
+  for (let i = start; i < stop; i += increment) {
+    r.push(i);
+  }
+  return r;
+}
+
+function printPocket() {
+  for (const z in pocket) {
+    const plane = pocket[z];
+    console.log(`z=${z}`);
+    for (const line of plane) {
+      console.log(line.join(""));
+    }
+  }
+}
+
+main();

2020/17/solution2.js

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+const fs = require("fs");
+
+const input = fs.readFileSync("input", "utf-8").trim();
+const startPlane = input.split("\n").map((line) => line.split(""));
+
+let pocket = [[startPlane]];
+
+function main() {
+  for (let step = 1; step <= 6; step++) {
+    const countActive = cycle();
+    console.log(`After ${step} steps: ${countActive}`);
+  }
+}
+
+function cycle() {
+  let squareLength = pocket[0][0].length;
+  let countActive = 0;
+  const nextPocket = [];
+  for (let w = -1; w < pocket.length + 1; w++) {
+    const space = [];
+    for (let z = -1; z < pocket.length + 1; z++) {
+      const plane = [];
+      for (let x = -1; x < squareLength + 1; x++) {
+        const line = [];
+        for (let y = -1; y < squareLength + 1; y++) {
+          const nextState = getState(w, z, x, y);
+          if (nextState === "#") countActive++;
+          line.push(nextState);
+        }
+        plane.push(line);
+      }
+      space.push(plane);
+    }
+    nextPocket.push(space);
+  }
+  pocket = nextPocket;
+
+  return countActive;
+}
+
+function getState(pw, pz, px, py) {
+  let activeNeighbors = 0;
+  for (const w of range(pw - 1, pw + 2)) {
+    for (const z of range(pz - 1, pz + 2)) {
+      for (const x of range(px - 1, px + 2)) {
+        for (const y of range(py - 1, py + 2)) {
+          if (pw === w && pz === z && px === x && py === y) continue;
+          if (isActive(w, z, x, y)) activeNeighbors++;
+        }
+      }
+    }
+  }
+  // console.log(`${py},${px},${py}: ${activeNeighbors}`);
+  if (isActive(pw, pz, px, py)) {
+    return activeNeighbors === 2 || activeNeighbors === 3 ? "#" : ".";
+  } else {
+    return activeNeighbors === 3 ? "#" : ".";
+  }
+}
+
+function isActive(w, z, x, y) {
+  return pocket[w]?.[z]?.[x]?.[y] === "#";
+}
+
+function range(start, stop, increment = 1) {
+  if (typeof stop === "undefined") {
+    stop = start;
+    start = 0;
+  }
+  const r = [];
+  for (let i = start; i < stop; i += increment) {
+    r.push(i);
+  }
+  return r;
+}
+
+main();