advent-of-code

Entries to advent of code, multiple years
git clone git://git.finwo.net/misc/advent-of-code
Log | Files | Refs

index.js (1925B)

      1 #!/usr/bin/env node
      2 
      3 const fs = require('node:fs');
      4 
      5 const banks = fs
      6   .readFileSync('input', 'utf-8')
      7   .split('\r\n').join('\n')
      8   .split('\r').join('\n')
      9   .split('\n')
     10   .map(str => str.trim())
     11   .filter(str => str)
     12   .map(bank => ({
     13     batteries: bank,
     14   }))
     15   ;
     16 
     17 // Part 1
     18 for(const bank of banks) {
     19   // Find the tens
     20   let highestTensVal = -1;
     21   let highestTensIdx = -1;
     22   for(const rating of ['9','8','7','6','5','4','3','2','1']) {
     23     const found = bank.batteries.indexOf(rating);
     24     if (found < 0) continue;
     25     if (found == (bank.batteries.length-1)) continue;
     26     highestTensVal = rating;
     27     highestTensIdx = found;
     28     break;
     29   }
     30   // Find the ones
     31   let highestOnesVal = -1;
     32   let highestOnesIdx = -1;
     33 
     34   for(const rating of ['9','8','7','6','5','4','3','2','1']) {
     35     const found = bank.batteries.indexOf(rating, highestTensIdx+1);
     36     if (found < 0) continue;
     37     highestOnesVal = rating;
     38     highestOnesIdx = found;
     39     break;
     40   }
     41 
     42   // Save it for the records
     43   bank.joltage2 = parseInt(`${highestTensVal}${highestOnesVal}`, 10);
     44 }
     45 
     46 // Part 2
     47 for(const bank of banks) {
     48 
     49   let construct = [];
     50   let currentIdx = -1;
     51   while(construct.length < 12) {
     52     let found = -1;
     53     for(const rating of ['9','8','7','6','5','4','3','2','1']) {
     54       found = bank.batteries.indexOf(rating, currentIdx + 1);
     55       if (found < 0) continue;
     56       if (found >= (bank.batteries.length + construct.length - 11)) {
     57         found = -1;
     58         continue;
     59       };
     60       currentIdx = found;
     61       construct.push(rating);
     62       break;
     63     }
     64     if (found < 0) {
     65       throw new Error("Could not find highest number");
     66     }
     67   }
     68 
     69   bank.joltage12 = BigInt(construct.join(''));
     70 }
     71 
     72 const part1 = banks.reduce((r,bank) => r+bank.joltage2, 0);
     73 const part2 = banks.reduce((r,bank) => r+bank.joltage12, 0n);
     74 
     75 process.stdout.write(`------[ Part 1: ${part1} ]------\n`);
     76 process.stdout.write(`------[ Part 2: ${part2} ]------\n`);