advent-of-code

commit 5797c6eea85391813f589527390d5f0d3d6d29d9
parent d66837d90c21187010e86d67bbe762d26cc88293
Author: finwo <finwo@pm.me>
Date:   Sat, 10 Dec 2022 16:06:30 +0100

2022/09 solution

Diffstat:
A
2022/day-09/index.js
 | 
78
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 78 insertions(+), 0 deletions(-)
diff --git a/2022/day-09/index.js b/2022/day-09/index.js
@@ -0,0 +1,78 @@
+const fs            = require('fs');
+const through       = require('through2');
+const line_for_line = require('../common/line-for-line');
+
+const x    = 0;
+const y    = 1;
+const head = 0;
+const pos  = Array(10).fill(0).map(() => [0,0]);
+const tail = pos.length - 1;
+
+const movements = {
+  U: [0,1],
+  D: [0,-1],
+  L: [-1,0],
+  R: [1,0],
+};
+
+const follows = [
+  [[-1, -1],[-1,-1],[ 0,-1],[ 1, -1],[ 1, -1]],
+  [[-1, -1],[ 0, 0],[ 0, 0],[ 0,  0],[ 1, -1]],
+  [[-1,  0],[ 0, 0],[ 0, 0],[ 0,  0],[ 1,  0]],
+  [[-1,  1],[ 0, 0],[ 0, 0],[ 0,  0],[ 1,  1]],
+  [[-1,  1],[-1, 1],[ 0, 1],[ 1,  1],[ 1,  1]],
+];
+
+const visited = [[0,0]];
+
+fs.createReadStream('input')
+// fs.createReadStream('input')
+  .pipe(line_for_line())
+
+  // Load grid
+  .pipe(through(function(line, enc, cb) {
+    line = line.toString();
+
+    const [ aDir, aCnt ] = line.split(' ');
+    const   iCnt         = parseInt(aCnt);
+
+    // Build head movement reference
+    const mv = movements[aDir];
+
+    // Run N steps
+    for(let i=0; i<iCnt; i++) {
+
+      // Move head
+      pos[head][x] += mv[x];
+      pos[head][y] += mv[y];
+
+      // Iterate over segments for follow movement
+      for(let i=head+1; i<pos.length; i++) {
+        const diff   = [ pos[i-1][x] - pos[i][x], pos[i-1][y] - pos[i][y] ];
+        const follow = follows[diff[y]+2][diff[x]+2];
+        pos[i][x] += follow[x];
+        pos[i][y] += follow[y];
+      }
+
+      // Track position visited
+      visited.push(
+        visited.find((p) => p[x] == pos[tail][x] && p[y] == pos[tail][y]) || [...pos[tail]]
+      );
+
+    }
+
+    cb();
+  }))
+
+  .on('finish', () => {
+
+    // So visited, so we can make it unique
+    let unique = 0;
+    visited.forEach((p,i) => {
+      if (visited.indexOf(p) == i) unique++;
+    });
+
+    console.log({ unique });
+
+    console.log('finish');
+  });