day 17 part 2, wow

.aocrunner.json

@@ -254,17 +254,17 @@
     {
       "part1": {
         "solved": true,
-        "result": null,
+        "result": "1,5,0,1,7,4,1,0,3",
         "attempts": [
           "1,4,0,1,1,0,1,0,3"
         ],
-        "time": null
+        "time": 0.057416
       },
       "part2": {
-        "solved": false,
+        "solved": true,
-        "result": null,
+        "result": "47910079998866",
         "attempts": [],
-        "time": null
+        "time": 8772.936208
       }
     },
     {

README.md

@@ -27,7 +27,7 @@
 [![Day](https://badgen.net/badge/14/%E2%98%85%E2%98%86/yellow)](src/day14)
 [![Day](https://badgen.net/badge/15/%E2%98%85%E2%98%85/green)](src/day15)
 [![Day](https://badgen.net/badge/16/%E2%98%85%E2%98%85/green)](src/day16)
-[![Day](https://badgen.net/badge/17/%E2%98%85%E2%98%86/yellow)](src/day17)
+[![Day](https://badgen.net/badge/17/%E2%98%85%E2%98%85/green)](src/day17)
 ![Day](https://badgen.net/badge/18/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/19/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/20/%E2%98%86%E2%98%86/gray)
@@ -181,9 +181,9 @@ Both parts: 132.546ms
 
 ```
 Day 17
-Time part 1: 0.064ms
+Time part 1: -
-Time part 2: -
+Time part 2: 8693.239ms
-Both parts: 0.064ms
+Both parts: 8693.239ms
 ```
 
 ```
@@ -243,8 +243,8 @@ Both parts: -
 ```
 
 ```
-Total stars: 32/50
+Total stars: 33/50
-Total time: 150841.277ms
+Total time: 159534.453ms
 ```
 
 <!--/RESULTS-->

src/day17/index.ts

@@ -1,10 +1,10 @@
 import run from "aocrunner"
 
 const parseInput = (rawInput: string) => {
-  const [registers, program] = rawInput.split('\n\n')
+  const [registers, program] = rawInput.split("\n\n")
   return {
-    registers: registers.split('\n').map(r => BigInt(r.split(": ")[1])),
+    registers: registers.split("\n").map((r) => BigInt(r.split(": ")[1])),
-    program: program.split(': ')[1].split(',').map(Number)
+    program: program.split(": ")[1].split(",").map(Number),
   }
 }
 
@@ -12,70 +12,65 @@ const mod = (a: bigint, b: bigint) => ((a % b) + b) % b
 
 const explainProgram = (program: number[]) => {
   let explanation = ""
-  const ops = [
+  const ops: ((x: number) => void)[] = [
-    x => `A = A >> ${combo(x)}`,
+    (x) => `A = A >> ${combo(x)}`,
-    x => `B = B XOR ${x}`,
+    (x) => `B = B XOR ${x}`,
-    x => `B = ${combo(x)} % 8`,
+    (x) => `B = ${combo(x)} % 8`,
-    x => `GOTO ${x}`,
+    (x) => `GOTO ${x}`,
-    x => `B = B XOR C`,
+    () => `B = B XOR C`,
-    x => `Output ${combo(x)} % 8`,
+    (x) => `Output ${combo(x)} % 8`,
-    x => `B = B >> ${combo(x)}`,
+    (x) => `B = B >> ${combo(x)}`,
-    x => `C = C >> ${combo(x)}`,
+    (x) => `C = C >> ${combo(x)}`,
   ]
-  const combo = x => "0123ABC"[x]
+  const combo = (x: number) => "0123ABC"[x]
   for (let i = 0; i < program.length; i += 2) {
-    const op = ops[program[i]](program[i+1])
+    const op = ops[program[i]](program[i + 1])
     explanation += `${i}: ${op}\n`
   }
-  return explanation.trim()
+  return explanation
 }
 
 const execute = (registers: bigint[], program: number[]) => {
-  let seenStates = new Set<string>()
   let [a, b, c] = registers
   let pointer = 0
   const output: number[] = []
   const getCombo = (n: number) => [0n, 1n, 2n, 3n, a, b, c][n]
   const ops: ((operand: number) => void)[] = [
-    n => { // adv
+    function adv(n) {
       a = a >> getCombo(n)
       pointer += 2
     },
-    n => { // bxl
+    function bxl(n) {
       b = b ^ BigInt(n)
       pointer += 2
     },
-    n => { // bst
+    function bst(n) {
       b = mod(getCombo(n), 8n)
       pointer += 2
     },
-    n => { // jnz
+    function jnz(n) {
       pointer = a === 0n ? pointer + 2 : n
     },
-    n => { // bxc
+    function bxc(_) {
       b = b ^ c
       pointer += 2
     },
-    n => { // out
+    function out(n) {
       output.push(Number(mod(getCombo(n), 8n)))
       pointer += 2
     },
-    n => { // bdv
+    function bdv(n) {
       b = a >> getCombo(n)
       pointer += 2
     },
-    n => { // cdv
+    function cdv(n) {
       c = a >> getCombo(n)
       pointer += 2
     },
   ]
   while (true) {
-    const thisState = [a,b,c,pointer].join()
-    if (seenStates.has(thisState)) {
-      return 'LOOP'
-    }
     if (pointer >= program.length) {
-      return output.join()
+      return output
     }
     const opcode = program[pointer]
     const operand = program[pointer + 1]
@@ -85,40 +80,53 @@ const execute = (registers: bigint[], program: number[]) => {
 
 const part1 = (rawInput: string) => {
   const { registers, program } = parseInput(rawInput)
-  return execute(registers, program)
+  return execute(registers, program).join()
 }
 
-
 const part2 = (rawInput: string) => {
-  const { registers: [_a, b, c], program } = parseInput(rawInput)
+  const {
+    registers: [_a, b, c],
+    program,
+  } = parseInput(rawInput)
   console.log(explainProgram(program))
-  // const target = program.join()
+
-  // let i = 1n
+  let i = 0n
-  // while (true) {
+  let found = 0
-  //   const result = execute([i, b, c], program)
+  while (true) {
-  //   if (result.length < target.length) i *= 2n
+    const result = execute([i, b, c], program)
-  //   if (result === target) {
+    console.log(`${i} ${result.join()}`)
-  //     return i
+    let matchCount = 0
-  //   }
+    for (let j = 0; j < result.length; j++) {
-  //   console.log(`${i} ${result}`)
+      if (result[result.length - 1 - j] === program[program.length - 1 - j]) {
-  //   i += 1n
+        matchCount++
-  // }
+      } else break
+    }
+    if (matchCount === program.length) {
+      return Number(i)
+    }
+    if (matchCount > found) {
+      i = i << (3n * BigInt(matchCount - found))
+      found = matchCount
+    } else {
+      i++
+    }
+  }
 }
 
 run({
-//   part1: {
+  part1: {
-//     tests: [
+    tests: [
-//       {
+      {
-//         input: `Register A: 729
+        input: `Register A: 729
-// Register B: 0
+Register B: 0
-// Register C: 0
+Register C: 0
 
-// Program: 0,1,5,4,3,0`,
+Program: 0,1,5,4,3,0`,
-//         expected: `4,6,3,5,6,3,5,2,1,0`,
+        expected: `4,6,3,5,6,3,5,2,1,0`,
-//       },
+      },
-//     ],
+    ],
-//     solution: part1,
+    solution: part1,
-//   },
+  },
   part2: {
     tests: [
       {