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Advent of Code 2021
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package main
import (
"log"
"math"
"os"
"strconv"
"strings"
"github.com/thoas/go-funk"
)
func main() {
inputBytes, _ := os.ReadFile("input.txt")
input := string(inputBytes)
log.Println("Puzzle 1:", puzzle1(input))
log.Println("Puzzle 2:", puzzle2(input))
}
func puzzle1(input string) int {
return do(input, false)
}
func puzzle2(input string) int {
return do(input, true)
}
func do(input string, puzzle2 bool) int {
// Read input
crabs := []int{}
for _, p := range strings.Split(input, ",") {
i, _ := strconv.Atoi(p)
crabs = append(crabs, i)
}
// Get min and max
minPos := funk.MinInt(crabs)
maxPos := funk.MaxInt(crabs)
// For each possible target position, calculate required fuel
minFuel := math.MaxInt
for target := minPos; target <= maxPos; target++ {
fuel := 0
for _, c := range crabs {
if puzzle2 {
if c == target {
continue
}
newFuel := 0
distance := funk.ShortIf(c > target, c-target, target-c).(int)
for i := 1; i <= distance; i++ {
// First step costs 1 fuel, second step costs 2 fuel, etc.
newFuel += i
}
fuel += newFuel
} else {
// Add distance to fuel
fuel += int(math.Abs(float64(c) - float64(target)))
}
}
// Check if we have a new minimum
if fuel < minFuel {
minFuel = fuel
}
}
return minFuel
}