2024:17 ⭐️⭐️

Author: mfloryan

2024/17/day17.js

@@ -0,0 +1,110 @@
+const fs = require('fs')
+const path = require('path')
+
+let input = fs.readFileSync(path.join(__dirname, 'input.txt'), { encoding: 'utf8' })
+
+const operand = {
+ 0: (cpu) => 0,
+ 1: (cpu) => 1,
+ 2: (cpu) => 2,
+ 3: (cpu) => 3,
+ 4: (cpu) => cpu.A,
+ 5: (cpu) => cpu.B,
+ 6: (cpu) => cpu.C,
+ 7: (cpu) => { throw ("Invalid operand 7") }
+}
+
+const opcodes = {
+ 0: (cpu, op) => { cpu.A = Math.floor(cpu.A / Math.pow(2, operand[op](cpu))); cpu.cp += 2 },
+ 1: (cpu, op) => { cpu.B = cpu.B ^ op; cpu.cp += 2 },
+ 2: (cpu, op) => { cpu.B = operand[op](cpu) % 8; cpu.cp += 2 },
+ 3: (cpu, op) => { if (cpu.A != 0) cpu.cp = op; else cpu.cp += 2 },
+ 4: (cpu, op) => { cpu.B = Number(BigInt(cpu.B) ^ BigInt(cpu.C)); cpu.cp += 2 },
+ 5: (cpu, op) => { cpu.out.push(operand[op](cpu) % 8); cpu.cp += 2 },
+ 6: (cpu, op) => { cpu.B = Math.floor(cpu.A / Math.pow(2, operand[op](cpu))); cpu.cp += 2 },
+ 7: (cpu, op) => { cpu.C = Math.floor(cpu.A / Math.pow(2, operand[op](cpu))); cpu.cp += 2 },
+}
+
+// 2,4 - bst: Set B to A % 8 (combo operand 4 means get value from register A)
+// 1,1 - bxl: XOR B with 1 
+// 7,5 - cdv: Set C to floor(A / 2^B) (combo operand 5 means get power from register B)
+// 0,3 - adv: Set A to floor(A / 2^3) (divides A by 8)
+// 1,4 - bxl: XOR B with 4
+// 4,4 - bxc: XOR B with C (operand ignored)
+// 5,5 - out: Output B % 8 (combo operand 5 means get value from register B)
+// 3,0 - jnz: If A ≠ 0, jump to position 0
+
+function runJsCode(initialA) {
+ let out = []
+
+ let a = initialA
+ do {
+ let b = a % 8
+ b = b ^ 1
+ let c = Math.floor(a / (2 ** b))
+ b = b ^ 4
+ b = Number(BigInt(b) ^ BigInt(c))
+ out.push(b % 8)
+ a = Math.floor(a / 8)
+ } while (a > 0)
+
+ return out
+}
+
+function run(cpu, code) {
+ cpu.cp = 0;
+ cpu.out = [];
+ do {
+ opcodes[code[cpu.cp]](cpu, code[cpu.cp + 1])
+ }
+ while (cpu.cp < code.length)
+ return cpu
+}
+
+let [cpuT, codeT] = input.split('\n\n')
+
+let cpu = cpuT.split('\n').map(l => {
+ let reg = l.substring(9).split(': ')
+ return [reg[0], parseInt(reg[1])]
+})
+
+let code = codeT.substring(8).split(',').map(Number)
+
+let computer = {
+ A: cpu[0][1],
+ B: cpu[1][1],
+ C: cpu[2][1],
+ cp: 0,
+ out: []
+}
+
+let newCpu = run(computer, code)
+console.log(newCpu.out.join(','))
+
+function check(sofar, expected, allOptions = []) {
+
+ if (sofar.length == expected.length) {
+ allOptions.push(sofar)
+ return
+ }
+
+ let options = []
+
+ for (let d = 0; d < 8; d++) {
+ let octal = sofar + d
+ let out = runJsCode(parseInt(octal, 8))
+ if (out.toReversed().every((v, i) => expected[expected.length - 1 - i] == v)) {
+ options.push(octal)
+ }
+ }
+
+ for (const option of options) {
+ check(option, expected, allOptions)
+ }
+}
+
+let expected = [2, 4, 1, 1, 7, 5, 0, 3, 1, 4, 4, 4, 5, 5, 3, 0]
+
+let options = []
+check('',expected, options)
+console.log( parseInt(options.toSorted()[0],8))

2024/17/input.txt

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+Register A: 30886132
+Register B: 0
+Register C: 0
+
+Program: 2,4,1,1,7,5,0,3,1,4,4,4,5,5,3,0