advent-of-code

commit 47b7fe31661ae1a6be1ed86a54b539484994e8f5
parent 36f3726b488bf16bef7c5d7fc1cc94d2145b4d46
Author: finwo <finwo@pm.me>
Date:   Sun,  4 Dec 2022 20:26:11 +0100

2022/04 solution

Diffstat:
A
2022/day-04/index.js
 | 
58
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 58 insertions(+), 0 deletions(-)
diff --git a/2022/day-04/index.js b/2022/day-04/index.js
@@ -0,0 +1,58 @@
+const fs            = require('fs');
+const through       = require('through2');
+const line_for_line = require('../common/line-for-line');
+
+let enclosed = 0;
+let overlapS  = 0;
+let overlapM  = 0;
+
+fs.createReadStream('input')
+  .pipe(line_for_line())
+
+  // Business logic
+  .pipe(through(function(line, enc, cb) {
+    line = line.toString();
+
+    const rangeA = line.split(',').shift().split('-').map(x => parseInt(x));
+    const rangeB = line.split(',').pop().split('-').map(x => parseInt(x));
+
+    if ((rangeA[0] <= rangeB[0]) && (rangeA[1] >= rangeB[1])) {
+      // Range A encloses range B
+      enclosed++;
+    } else if ((rangeA[0] >= rangeB[0]) && (rangeA[1] <= rangeB[1])) {
+      // Range B encloses range A
+      enclosed++;
+    }
+
+    this.push(line);
+    cb();
+  }))
+
+  // Business logic
+  .pipe(through(function(line, enc, cb) {
+    line = line.toString();
+
+    const rangeA = line.split(',').shift().split('-').map(x => parseInt(x));
+    const rangeB = line.split(',').pop().split('-').map(x => parseInt(x));
+
+    // Thanks to https://stackoverflow.com/a/64745177
+    // Took me longer to figure out the brainfart than I'm willing to admit
+    let overlapSO = Math.max(rangeA[0], rangeB[0]) <= Math.min(rangeA[1], rangeB[1]);
+    let overlapMe = 
+      ((rangeA[0] <= rangeB[0]) && (rangeA[1] >= rangeB[0])) || // rangeB[0] within rangeA
+      ((rangeA[0] <= rangeB[1]) && (rangeA[1] >= rangeB[1])) || // rangeB[1] within rangeA
+      ((rangeB[0] <= rangeA[0]) && (rangeB[1] >= rangeA[0])) || // rangeA[0] within rangeB
+      ((rangeB[0] <= rangeA[1]) && (rangeB[1] >= rangeA[1]))    // rangeA[1] within rangeB
+    ;
+
+    if (overlapSO) overlapS++;
+    if (overlapMe) overlapM++;
+
+    cb();
+  }))
+
+  .on('finish', () => {
+    // done
+    console.log('Enclosed', enclosed);
+    console.log('Overlap', { overlapS, overlapM });
+  });