108 lines
2.6 KiB
Go
108 lines
2.6 KiB
Go
package main
|
|
|
|
import (
|
|
"bufio"
|
|
"bytes"
|
|
"fmt"
|
|
"os"
|
|
"strconv"
|
|
)
|
|
|
|
func main() {
|
|
fishies, err := readInput("input")
|
|
if err != nil {
|
|
fmt.Printf("Error reading or something\n%s", err)
|
|
return
|
|
}
|
|
|
|
fmt.Printf("Initializing fishies array...\n")
|
|
fish, _ := splitFishies(fishies)
|
|
fmt.Printf("Done!\n")
|
|
|
|
fishiesptr := &fish
|
|
// Run for i days
|
|
for i := 0; i < 256; i++ {
|
|
newfishies, _ := nextDay(*fishiesptr)
|
|
fishiesptr = &newfishies
|
|
amount := countFishies(*fishiesptr)
|
|
fmt.Printf("On day %d: there are %d fishies\n", i+1, amount)
|
|
}
|
|
}
|
|
|
|
func countFishies(fishies []int) int {
|
|
counter := 0
|
|
for i := 0; i < len(fishies); i++ {
|
|
counter += fishies[i]
|
|
}
|
|
return counter
|
|
}
|
|
|
|
// Read the fishies slice and returns the slice of new fishies
|
|
func nextDay(fishies []int) ([]int, error) {
|
|
// Move fishies at 0 into buffer, move all fishies down the stack
|
|
// Add the 0 day fishies (from buffer) to the fishies at day 6
|
|
// Add the same amount of fishies from buffer to the 8 day counter
|
|
// Return the new splits
|
|
|
|
buffer := fishies[0]
|
|
for i := 0; i < len(fishies)-1; i++ {
|
|
fishies[i] = fishies[i+1]
|
|
}
|
|
fishies[6] += buffer
|
|
fishies[8] = buffer
|
|
return fishies, nil
|
|
}
|
|
|
|
// Returns a slice of the amount of fishies per day, ordered from 0 days to 8
|
|
func splitFishies(fishies []int) ([]int, error) {
|
|
fishiesButSplit := make([]int, 9)
|
|
for i := 0; i < len(fishies); i++ {
|
|
fishiesButSplit[fishies[i]]++
|
|
}
|
|
|
|
return fishiesButSplit, nil
|
|
}
|
|
|
|
func readInput(inputfile string) ([]int, error) {
|
|
file, err := os.OpenFile(inputfile, 0, 0)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer file.Close()
|
|
|
|
splitfunc := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
|
|
nextIndex := bytes.IndexByte(data, ',')
|
|
if nextIndex > 0 {
|
|
// Returning the next position aka taking only the stuff up to nextIndex and slicing off everything else
|
|
buffer := data[:nextIndex]
|
|
// nextIndex plus 1 because index is at the comma, we want the next number
|
|
return nextIndex + 1, bytes.TrimSpace(buffer), nil
|
|
}
|
|
|
|
// If we are at the end of the buffer, then return the entire buffer, but only if there is data
|
|
if atEOF {
|
|
if len(data) > 0 {
|
|
return len(data), bytes.TrimSpace(data), nil
|
|
}
|
|
}
|
|
|
|
// https://github.com/kgrz/reading-files-in-go/blob/master/comma-separated-string.go
|
|
// For more info
|
|
return 0, nil, nil
|
|
}
|
|
|
|
scanner := bufio.NewScanner(file)
|
|
scanner.Split(splitfunc)
|
|
|
|
fishies := make([]int, 0)
|
|
for scanner.Scan() {
|
|
fish, err := strconv.Atoi(scanner.Text())
|
|
if err != nil {
|
|
fmt.Printf("Error converting string to integer\n")
|
|
return nil, err
|
|
}
|
|
fishies = append(fishies, fish)
|
|
}
|
|
return fishies, nil
|
|
}
|