From 13ff73d6575ada33f8106ee1d339236f2bf02a5a Mon Sep 17 00:00:00 2001
From: Alexander Rundberg <alex@gwai.se>
Date: Wed, 18 Dec 2024 13:47:59 +0100
Subject: [PATCH] Add solution day 17 part 2
---
README.md | 2 +-
solutions/day17/main.go | 69 ++++++++++++++++++++++++++++-------------
2 files changed, 48 insertions(+), 23 deletions(-)
diff --git a/README.md b/README.md
index db7ceb1..eea3d57 100644
--- a/README.md
+++ b/README.md
@@ -49,7 +49,7 @@ automatically rebuilt and redeployed every time the `common` module or their own
| 01 | ⭐ ⭐ | 14 | ⭐ ⭐ |
| 02 | ⭐ ⭐ | 15 | ⭐ ⭐ |
| 03 | ⭐ ⭐ | 16 | ⭐ 🥸 |
-| 04 | ⭐ ⭐ | 17 | ⭐ |
+| 04 | ⭐ ⭐ | 17 | ⭐ ⭐ |
| 05 | ⭐ ⭐ | 18 | ⭐ ⭐ |
| 06 | ⭐ ⭐ | 19 | |
| 07 | ⭐ ⭐ | 20 | |
diff --git a/solutions/day17/main.go b/solutions/day17/main.go
index c9ce79d..2e3e070 100644
--- a/solutions/day17/main.go
+++ b/solutions/day17/main.go
@@ -3,6 +3,8 @@ package main
import (
"fmt"
"github.com/terminalnode/adventofcode2024/common"
+ "strconv"
+ "strings"
)
func main() {
@@ -28,38 +30,61 @@ func part2(
return fmt.Sprintf("Failed to parse machine: %v", err)
}
- lenSeq := len(m.seq)
- initA := int64(0)
+ maxIdx := len(m.seq) - 1
+ octArr := make([]int, len(m.seq))
+ octIdx := 0
initB := m.b
initC := m.c
- for initA = 0; true; initA++ {
- m.run(lenSeq)
- if compareSeqOut(m, lenSeq) {
- break
- }
- m.a = initA
+
+ for {
+ seqIdx := maxIdx - octIdx
+
+ // Rig the machine
+ octArr[octIdx] += 1
m.b = initB
m.c = initC
m.out = m.out[:0]
- m.pos = 0
+
+ m.a, err = arrayToOct(octArr)
+ if err != nil {
+ return fmt.Sprintf("Failed to read %v as octal string: %v", octArr, err)
+ }
+
+ // Run the program and verify output
+ m.run(maxIdx + 1)
+ correct := m.out[seqIdx] == m.seq[seqIdx]
+
+ if octIdx == maxIdx && correct {
+ break
+ } else if correct {
+ octIdx++
+ octArr[octIdx] = -1
+ }
+
+ for octArr[octIdx] == 7 {
+ octArr[octIdx] = 0
+ octIdx--
+ }
}
- return fmt.Sprintf("Registry A should be %d", initA-1)
+ final, err := arrayToOct(octArr)
+ if err != nil {
+ return fmt.Sprintf("Solved it, but failed to extract number: %v", err)
+ }
+ return fmt.Sprintf("Registry A should be %d", final)
}
-func compareSeqOut(
- m machine,
- lenSeq int,
-) bool {
- if len(m.out) != lenSeq {
- return false
+func arrayToOct(
+ arr []int,
+) (int64, error) {
+ strArr := make([]string, len(arr))
+ for i, n := range arr {
+ strArr[i] = strconv.Itoa(n)
}
- for i, seq := range m.seq {
- if m.out[i] != seq {
- return false
- }
+ oct, err := strconv.ParseInt(strings.Join(strArr, ""), 8, 64)
+ if err != nil {
+ return 0, err
}
-
- return true
+ return oct, nil
}