12.md

Day 12

Part 1

What is the sum of all numbers in the JSON? (The are no numeric strings in the JSON.)

const input = '{"a":{"b":4},"c":-1}'

const numbers = input.match(/(-?\d+)/g)
const part1 = numbers.reduce((total, number) => total + Number(number), 0)
console.log('Part 1:', part1)

Flems link in Part 2.

Hah, I cheated! My fastest puzzle solution so far. 😜

Part 2

Ignore objects (and their children) that have any property with the value "red". Do this only for objects, not arrays. What's the sum now?

Guess we'll have to actually parse the JSON:

const json = JSON.parse(input)
const part2 = Object.values(json).reduce(sum, 0)
console.log('Part 2:', part2)

function sum(total, value) {
  // Strings can be ignored because there are no numeric strings
  if (typeof value === 'string') {
    return total
  }

  if (typeof value === 'number') {
    return total + value
  }

  if (Array.isArray(value)) {
    return total + value.reduce(sum, 0)
  }

  if (typeof value === 'object') {
    const values = Object.values(value)
    return values.includes('red') ? total : total + values.reduce(sum, 0)
  }

  throw new Error(`value "${value}" has invalid type "${typeof value}"`)
}

Try out the final code on flems.io

What did I learn?

Nothing, this was an easy puzzle. 😌