106 lines
1.8 KiB
Go
106 lines
1.8 KiB
Go
package main
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import (
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"bufio"
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"bytes"
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"fmt"
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"log"
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"os"
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"strconv"
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)
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func main() {
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inp := []byte(StdinToString())
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fmt.Println("= Part 1 =")
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fmt.Println(part1(inp))
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fmt.Println("\n= Part 2 =")
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fmt.Println(part2(inp))
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}
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func part1(inp []byte) int {
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last := inp
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curr := react(last)
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for !bytes.Equal(last, curr) {
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last = curr
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curr = react(last)
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}
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return len(curr)
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}
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// useShortest will skip runs where there are fewer letters in the input than the current shortest...
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// It reduced _my_ runtime by about 3 minutes, but may fail depending on your input
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var useShortest bool
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func part2(inp []byte) int {
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// If yours fails, try setting this to false
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useShortest = true
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shortest := len(inp)
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var shortestCount int
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var count int
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for i := 65; i <= 90; i++ {
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var try []byte
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if useShortest {
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count = countByte(inp, byte(i))
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if count < shortestCount {
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continue
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}
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}
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for j := range inp {
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if int(inp[j]) == i || int(inp[j]) == i+32 {
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continue
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}
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try = append(try, inp[j])
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}
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v := part1(try)
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if v < shortest {
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shortest = v
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shortestCount = count
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}
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}
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return shortest
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}
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func countByte(h []byte, n byte) int {
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var ret int
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for i := range h {
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if h[i] == n {
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ret++
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}
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}
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return ret
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}
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func react(v []byte) []byte {
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var ret []byte
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for i := 0; i < len(v); i++ {
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if i < len(v)-1 && sameDecase(v[i], v[i+1]) {
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i++
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continue
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}
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ret = append(ret, v[i])
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}
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return ret
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}
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func StdinToString() string {
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var input string
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scanner := bufio.NewScanner(os.Stdin)
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for scanner.Scan() {
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input += scanner.Text()
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}
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return input
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}
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func Atoi(i string) int {
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var ret int
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var err error
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if ret, err = strconv.Atoi(i); err != nil {
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log.Fatal("Invalid Atoi")
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}
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return ret
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}
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func sameDecase(val1, val2 byte) bool {
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return val1+32 == val2 || val2+32 == val1
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}
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