Day 5

05/part2.js

@@ -0,0 +1,64 @@
+const fs = require('fs')
+const readline = require('readline');
+
+const readInterface = readline.createInterface({
+    input: fs.createReadStream('input'),
+    console: false
+});
+
+// [[x,y], [x,y], ...]
+let seats = [];
+
+function makeArray(n) {
+  let ary = new Array(n);
+  for(i=0; i<n; i++) {
+    ary[i] = i;
+  }
+
+  return ary;
+}
+
+readInterface.on('line', function(line) {
+  const rowSpec = line.substring(0, 7);
+  const colSpec = line.substring(7, 10);
+
+  let row = rowSpec.split('').reduce(function(range, char) {
+    const half = Math.floor(range.length / 2);
+
+    let r2 = range;
+    switch(char) {
+    case 'F': r2 = range.slice(0, half+1); break;
+    case 'B': r2 = range.slice(half, range.length); break;
+    };
+
+    return r2;
+  }, makeArray(128));
+  
+  let col = colSpec.split('').reduce(function(range, char) {
+    const half = Math.floor(range.length / 2);
+
+    let r2 = range;
+    switch(char) {
+    case 'L': r2 = range.slice(0, half+1); break;
+    case 'R': r2 = range.slice(half,range.length); break;
+    };
+
+    return r2;
+  }, makeArray(8));
+
+  seats.push([col[0], row[0]]);
+});
+
+readInterface.on('close', function(line) {
+  let seatIDs = new Set( seats.map((seat) => seat[1]*8 + seat[0]).sort((a,b) => a-b ) );
+
+  for (x=0; x<8; x++) {
+    for(y=0; y<128; y++) {
+      let seatID = y*8+x;
+      if (!seatIDs.has(seatID) && seatIDs.has(seatID-1) && seatIDs.has(seatID+1)) {
+        console.log(seatID);
+        break;
+      }
+    }
+  }
+});