180 lines
2.8 KiB
Go
180 lines
2.8 KiB
Go
package main
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import (
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"bufio"
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_ "embed"
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"fmt"
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"strings"
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aoc "go.sour.is/advent-of-code-2023"
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)
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var log = aoc.Log
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func main() { aoc.MustResult(aoc.Runner(run)) }
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type result struct {
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valuePT1 int
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valuePT2 int
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}
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func (r result) String() string { return fmt.Sprintf("%#v", r) }
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func run(scan *bufio.Scanner) (*result, error) {
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maps := []Map{}
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m := Map{}
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r := &result{}
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for scan.Scan() {
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text := scan.Text()
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if text == "" {
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maps = append(maps, m)
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m = Map{}
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} else {
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m = append(m, []rune(text))
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}
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}
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maps = append(maps, m)
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for _, m := range maps {
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sum, sum2 := findSmudge(m)
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if sum == -1 || sum2 == -1 {
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mr := Map(aoc.Transpose(m))
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Hsum, Hsum2 := findSmudge(mr)
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if sum2 == -1 {
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sum2 = Hsum2 * 100
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}
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if sum == -1 {
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sum = Hsum * 100
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}
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}
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r.valuePT1 += sum
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r.valuePT2 += sum2
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}
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return r, nil
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}
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type Map [][]rune
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func (m Map) String() string {
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var buf strings.Builder
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for i, row := range m {
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if i == 0 {
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fmt.Fprint(&buf, " ")
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for j := range row {
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fmt.Fprintf(&buf, "%d", j)
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}
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fmt.Fprint(&buf, "\n")
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}
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fmt.Fprintf(&buf, "%d ", i)
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buf.WriteRune(' ')
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buf.WriteString(string(row))
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buf.WriteRune('\n')
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}
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buf.WriteRune('\n')
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return buf.String()
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}
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// func findReflection(m Map) (int, bool) {
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// candidates := make(map[int]bool)
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// var candidateList []int
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// for _, row := range m {
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// for col := 1; col < len(row); col++ {
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// if v, ok := candidates[col]; !ok || v {
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// candidates[col], _ = reflects(row[:col], row[col:])
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// }
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// }
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// candidateList = all(candidates)
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// if len(candidateList) == 0 {
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// return 0, false
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// }
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// }
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// if len(candidateList) == 1 {
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// return candidateList[0], true
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// }
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// return 0, false
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// }
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type level struct {
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blips int
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nequal int
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fail bool
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}
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func findSmudge(m Map) (int, int) {
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candidates := make(map[int]level)
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for _, row := range m {
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for col := 1; col < len(row); col++ {
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candidate := candidates[col]
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if candidate.fail {
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continue
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}
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eq, bl := reflects(row[:col], row[col:])
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if !eq {
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candidate.nequal++
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}
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candidate.blips += bl
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if candidate.nequal > 1 || candidate.blips > 1 {
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candidate.fail = true
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}
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candidates[col] = candidate
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}
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}
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a, b := -1, -1
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for i, cand := range candidates {
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if !cand.fail && cand.blips == 1 {
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b = i
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}
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if !cand.fail && cand.blips == 0 {
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a = i
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}
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}
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return a, b
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}
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func reflects(a, b []rune) (bool, int) {
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c := min(len(a), len(b))
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a = append([]rune{}, a...)
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b = append([]rune{}, b...)
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aoc.Reverse(a)
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a = a[:c]
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b = b[:c]
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blips := 0
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for i := range a {
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if a[i] != b[i] {
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blips++
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}
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}
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return blips == 0, blips
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}
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func all[T comparable](m map[T]bool) []T {
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lis := make([]T, 0, len(m))
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for k, v := range m {
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if v {
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lis = append(lis, k)
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}
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}
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return lis
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}
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