9.1 and 9.2. 9.2 took forever to figure out

2022/9/index.js

@@ -0,0 +1,82 @@
+
+const fs = require('fs/promises');
+
+const tailVisited = {'0-0': true};
+
+let hx = 0;
+let hy = 0;
+let tx = 0;
+let ty = 0;
+
+let lastHead = [0,0];
+
+const moveRope = (direction) =>  {
+  console.log("Moving ", direction);
+  lastHead = [hx, hy];
+  switch (direction) {
+    case "R":
+      hx += 1;
+      break;
+    case "L":
+      hx -= 1;
+      break;
+    case "U":
+      hy -= 1;
+      break;
+    case "D":
+      hy += 1;
+      break;
+  }
+
+  if(Math.max(Math.abs(hx - tx), Math.abs(hy - ty)) > 1) {
+    [tx, ty ] = lastHead;
+    console.log("Moving Tail to: ", tx, ", ", ty);
+    tailVisited[`${tx}-${ty}`] = true;
+  }
+}
+
+const printGraph = () => {
+  console.log("\n\n");
+  for(let y = -15; y <= 15; y++) {
+    const row = ["·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·", "·"].map((spot, i) => {
+        const x = i - 15;
+        let ch = "·";
+        if(!(y % 5) && !(x % 5)) {
+          ch = "▪";
+        }
+        if(y === 0 && x === 0) {
+          ch = "0";
+        }
+        if(y === ty && x === tx) {
+          ch = "T";
+        }
+        if(y === hy && x === hx) {
+          ch = "H";
+        }
+        return ch;
+      });
+    console.log(row.join(""));
+  }
+  console.log("\n\n");
+};
+
+(async () => {
+  const input = await fs.readFile("./input.txt", 'utf8');
+
+  const lines = input.split("\n").map(t => t.split(" "));
+
+  //printGraph();
+  for (const [direction, times] of lines) {
+    for(let i = 0; i < times; ++i) {
+      moveRope(direction);
+      //printGraph();
+    }
+  }
+
+  console.log(Object.values(tailVisited).length);
+})();

2022/9/index2.js

@@ -0,0 +1,135 @@
+
+const fs = require('fs/promises');
+
+const tailVisited = {'0~0': true};
+
+const rope = [[0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0]];
+
+const keypress = async () => {
+  process.stdin.setRawMode(true)
+  return new Promise(resolve => process.stdin.once('data', data => {
+    const byteArray = [...data]
+    if (byteArray.length > 0 && byteArray[0] === 3) {
+      console.log('^C')
+      process.exit(1)
+    }
+    process.stdin.setRawMode(false)
+    resolve()
+  }))
+}
+
+const moveRope = (direction) => {
+  const lastSpot = [rope[0][0], rope[0][1]];
+  switch (direction) {
+    case "R":
+      rope[0][0] += 1;
+      break;
+    case "L":
+      rope[0][0] -= 1;
+      break;
+    case "U":
+      rope[0][1] -= 1;
+      break;
+    case "D":
+      rope[0][1] += 1;
+      break;
+  }
+  for(let i = 1; i < rope.length; ++i) {
+    rope[i] = moveSeg(rope[i], i)
+  }
+}
+
+const moveSeg = ([x, y], i) =>  {
+  if(i === rope.length) return;
+  const seg = rope[i - 1];
+  //console.log("uhh: ", rope, " ", i, " ", seg);
+  const [lx, ly] = seg;
+    V= rope[i - 1];
+  if(lx === x) {
+    if(ly === y + 2) {
+      return [x, y + 1];
+    }
+    if(ly === y - 2) {
+      return[x, y - 1];
+    }
+  }
+  if(ly === y) {
+    if(lx === x + 2) {
+      return [x + 1, y];
+    }
+    if(lx === x - 2) {
+      return rope[i] = [x - 1, y];
+    }
+  }
+  if(Math.max(Math.abs(x - lx), Math.abs(y - ly)) > 1) {
+    const xDiff = lx - x;
+    const yDiff = ly - y;
+    if(xDiff === 0 || yDiff === 0) {
+      console.log([x, y, lx, ly])
+      console.log("ROPE: ", rope);
+    }
+    return [x + xDiff/Math.abs(xDiff), y + yDiff/Math.abs(yDiff)];
+  }
+
+  return [x, y];
+}
+
+const printGraph = () => {
+  console.log("\n");
+  console.log(rope);
+  console.log("\n");
+  for(let y = -15; y <= 15; y++) {
+    const row = ["·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·",
+      "·", "·", "·", "·", "·", "·"].map((spot, i) => {
+        const x = i - 15;
+        const [hx, hy] = rope[0];
+        const [tx, ty] = rope[9];
+        let ch = "·";
+        if(!(y % 5) && !(x % 5)) {
+          ch = "▪";
+        }
+        if(y === 0 && x === 0) {
+          ch = "0";
+        }
+        if(y === ty && x === tx) {
+          ch = "T";
+        }
+        rope.slice(0, -1).reverse().forEach(([a, b], j) => {
+          if(a === x && b === y) {
+            ch = j+1;
+          }
+        });
+        if(y === hy && x === hx) {
+          ch = "H";
+        }
+        return ch;
+      });
+    console.log(row.join(""));
+  }
+  console.log("\n\n");
+};
+
+(async () => {
+  const input = await fs.readFile("./input.txt", 'utf8');
+
+  const lines = input.split("\n").map(t => t.split(" "));
+
+  //printGraph();
+  for (const [direction, times] of lines) {
+    for(let i = 0; i < times; ++i) {
+      //await keypress();
+      console.log("Moving ", direction);
+      moveRope(direction);
+      //printGraph();
+      tailVisited[`${rope[9][0]}~${rope[9][1]}`] = true;
+
+    }
+  }
+      console.log(tailVisited);
+
+  console.log(Object.values(tailVisited).length);
+})();