Solution in JS
I used an object to represent the grid to make counting the "painted" block easier.
Had a bit of trouble realizing that the top left of the grid is 0,0 and not the bottom left :)
const INSTRUCTIONS = { ADD: 1, MULT: 2, INPUT: 3, OUTPUT: 4, JUMP_IF_TRUE: 5, JUMP_IF_FALSE: 6, LESS_THAN: 7, EQUALS: 8, ADJUST_RELATIVE_BASE: 9, HALT: 99 } function runProgram(instructions) { instructions = instructions.slice() return function* amplifier() { let lastOutput = null let relativeBase = 0 for (let i = 0; i < instructions.length; ++i) { const instruction = instructions[i] const parsed = String(instruction) .padStart(5, '0') .split('') const getValue = (value, mode = '0') => { if (mode === '0') { return instructions[value] || 0 } else if (mode === '1') { return value } else if (mode === '2') { return instructions[relativeBase + value] || 0 } } const setValue = (index, value, mode = '0') => { if (mode === '0') { instructions[index] = value } else if (mode === '2') { instructions[relativeBase + index] = value } } const opCode = Number(parsed.slice(3).join('')) const modes = parsed.slice(0, 3) switch (opCode) { case INSTRUCTIONS.ADD: { const x = getValue(instructions[++i], modes[2]) const y = getValue(instructions[++i], modes[1]) setValue(instructions[++i], x + y, modes[0]) break } case INSTRUCTIONS.MULT: { const x = getValue(instructions[++i], modes[2]) const y = getValue(instructions[++i], modes[1]) setValue(instructions[++i], x * y, modes[0]) break } case INSTRUCTIONS.INPUT: { setValue(instructions[++i], yield { type: 'INPUT' }, modes[2]) break } case INSTRUCTIONS.OUTPUT: { lastOutput = getValue(instructions[++i], modes[2]) yield { type: 'OUTPUT', value: lastOutput } break } case INSTRUCTIONS.JUMP_IF_TRUE: { const compare = getValue(instructions[++i], modes[2]) const jumpTo = getValue(instructions[++i], modes[1]) - 1 if (compare != 0) { i = jumpTo } break } case INSTRUCTIONS.JUMP_IF_FALSE: { const compare = getValue(instructions[++i], modes[2]) const jumpTo = getValue(instructions[++i], modes[1]) - 1 if (compare == 0) { i = jumpTo } break } case INSTRUCTIONS.LESS_THAN: { const x = getValue(instructions[++i], modes[2]) const y = getValue(instructions[++i], modes[1]) setValue(instructions[++i], x < y ? 1 : 0, modes[0]) break } case INSTRUCTIONS.EQUALS: { const x = getValue(instructions[++i], modes[2]) const y = getValue(instructions[++i], modes[1]) setValue(instructions[++i], x === y ? 1 : 0, modes[0]) break } case INSTRUCTIONS.ADJUST_RELATIVE_BASE: { const adjustBy = getValue(instructions[++i], modes[2]) relativeBase += adjustBy break } case INSTRUCTIONS.HALT: return lastOutput } } } } const directions = { UP: 0, RIGHT: 1, DOWN: 2, LEFT: 3 } const modulo = (x, n) => ((x % n) + n) % n const runRobotProgram = (robot, initialBlockColor = 0) => { const grid = {} let location = [0, 0] grid[location.join(':')] = initialBlockColor let direction = directions.UP robot.next() while (true) { const input = grid[location.join(':')] || 0 const { value: { value: color } } = robot.next(input) grid[location.join(':')] = color const { value: { value: turn } } = robot.next() const { done } = robot.next() if (done) return { grid } if (turn === 0) { direction = modulo(direction - 1, 4) } else if (turn === 1) { direction = (direction + 1) % 4 } if (direction === directions.DOWN) { location = [location[0], location[1] + 1] } else if (direction === directions.RIGHT) { location = [location[0] + 1, location[1]] } else if (direction === directions.UP) { location = [location[0], location[1] - 1] } else if (direction === directions.LEFT) { location = [location[0] - 1, location[1]] } } } function printGrid(grid) { const [[minX, maxX], [minY, maxY]] = Object.keys(grid) .map(x => x.split(':').map(Number)) .reduce( (state, [x, y]) => { if (state[0][0] > x) state[0][0] = x if (state[0][1] < x) state[0][1] = x if (state[1][0] > y) state[1][0] = y if (state[1][1] < y) state[1][1] = y return state }, [ [Infinity, -Infinity], [Infinity, -Infinity] ] ) let gridMap = '' for (let y = minY; y <= maxY; ++y) { for (let x = minX; x <= maxX; ++x) { gridMap += grid[`${x}:${y}`] === 1 ? '#' : ' ' } gridMap += '\n' } return gridMap } function part1(instructions) { const { grid } = runRobotProgram(runProgram(instructions)()) const gridMap = printGrid(grid) console.log(gridMap) console.log(Object.keys(grid).length) } function part2(instructions) { const { grid } = runRobotProgram(runProgram(instructions)(), 1) const gridMap = printGrid(grid) console.log(gridMap) } const input = require('fs') .readFileSync(require('path').resolve(__dirname, './input.txt')) .toString() const instructions = input.split(',').map(Number) part1(instructions) part2(instructions)
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Solution in JS
I used an object to represent the grid to make counting the "painted" block easier.
Had a bit of trouble realizing that the top left of the grid is 0,0 and not the bottom left :)