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2018 day 14 complete

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Brian Buller 2018-12-14 12:58:05 -06:00
parent 52629a7b9c
commit c96141ea49
2 changed files with 196 additions and 0 deletions
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95
2018/day14/day14.go Normal file
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package main
import (
"fmt"
"log"
"os"
"strconv"
"strings"
)
var input string
var recipes []byte
var elfLocations []int
func main() {
input = "290431"
if len(os.Args) > 1 {
input = os.Args[1]
}
//part1()
part2()
}
func part1() {
fmt.Println("= Part 1 =")
elfLocations = []int{0, 1}
recipes = []byte{'3', '7'}
inp := Atoi(input)
for len(recipes) < inp+10 {
tick()
moveElves()
}
fmt.Println(string(recipes[inp:]))
fmt.Println()
}
func part2() {
fmt.Println("= Part 2 =")
elfLocations = []int{0, 1}
recipes = []byte{'3', '7'}
for i := 0; i < 30000000; i++ {
tick()
moveElves()
}
fmt.Println(strings.Index(string(recipes), input))
}
func tick() {
r1, r2 := getElfRecipes()
//fmt.Println(r1, r2, strconv.Itoa(r1+r2))
sum := []byte(strconv.Itoa(int(r1 - '0' + r2 - '0')))
recipes = append(recipes, sum...)
}
func getElfRecipes() (byte, byte) {
lgt := len(recipes)
if lgt <= elfLocations[0] || lgt <= elfLocations[1] {
fmt.Println(elfLocations[0], elfLocations[1], len(recipes))
os.Exit(0)
}
return recipes[elfLocations[0]], recipes[elfLocations[1]]
}
func moveElves() {
for num := range elfLocations {
newLoc := (elfLocations[num] + int(recipes[elfLocations[num]]-'0') + 1) % len(recipes)
elfLocations[num] = newLoc
}
}
func testForInput() bool {
if len(recipes) < len(input) {
return false
}
for i := 0; i < len(input); i++ {
idx := len(recipes) - len(input) + i
if recipes[idx] != input[i] {
return false
}
//fmt.Println(recipes[idx], "==", inputSlice[i])
}
idx := len(recipes) - len(input)
fmt.Println(recipes[idx:], input)
return true
}
func Atoi(i string) int {
var ret int
var err error
if ret, err = strconv.Atoi(i); err != nil {
log.Fatal("Invalid Atoi")
}
return ret
}

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2018/day14/problem Normal file
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Advent of Code
--- Day 14: Chocolate Charts ---
You finally have a chance to look at all of the produce moving around. Chocolate, cinnamon, mint, chili
peppers, nutmeg, vanilla... the Elves must be growing these plants to make hot chocolate! As you realize
this, you hear a conversation in the distance. When you go to investigate, you discover two Elves in what
appears to be a makeshift underground kitchen/laboratory.
The Elves are trying to come up with the ultimate hot chocolate recipe; they're even maintaining a scoreboard
which tracks the quality score (0-9) of each recipe.
Only two recipes are on the board: the first recipe got a score of 3, the second, 7. Each of the two Elves
has a current recipe: the first Elf starts with the first recipe, and the second Elf starts with the second
recipe.
To create new recipes, the two Elves combine their current recipes. This creates new recipes from the digits
of the sum of the current recipes' scores. With the current recipes' scores of 3 and 7, their sum is 10, and
so two new recipes would be created: the first with score 1 and the second with score 0. If the current
recipes' scores were 2 and 3, the sum, 5, would only create one recipe (with a score of 5) with its single
digit.
The new recipes are added to the end of the scoreboard in the order they are created. So, after the first
round, the scoreboard is 3, 7, 1, 0.
After all new recipes are added to the scoreboard, each Elf picks a new current recipe. To do this, the Elf
steps forward through the scoreboard a number of recipes equal to 1 plus the score of their current recipe.
So, after the first round, the first Elf moves forward 1 + 3 = 4 times, while the second Elf moves forward 1
+ 7 = 8 times. If they run out of recipes, they loop back around to the beginning. After the first round,
both Elves happen to loop around until they land on the same recipe that they had in the beginning; in
general, they will move to different recipes.
Drawing the first Elf as parentheses and the second Elf as square brackets, they continue this process:
(3)[7]
(3)[7] 1 0
3 7 1 [0](1) 0
3 7 1 0 [1] 0 (1)
(3) 7 1 0 1 0 [1] 2
3 7 1 0 (1) 0 1 2 [4]
3 7 1 [0] 1 0 (1) 2 4 5
3 7 1 0 [1] 0 1 2 (4) 5 1
3 (7) 1 0 1 0 [1] 2 4 5 1 5
3 7 1 0 1 0 1 2 [4](5) 1 5 8
3 (7) 1 0 1 0 1 2 4 5 1 5 8 [9]
3 7 1 0 1 0 1 [2] 4 (5) 1 5 8 9 1 6
3 7 1 0 1 0 1 2 4 5 [1] 5 8 9 1 (6) 7
3 7 1 0 (1) 0 1 2 4 5 1 5 [8] 9 1 6 7 7
3 7 [1] 0 1 0 (1) 2 4 5 1 5 8 9 1 6 7 7 9
3 7 1 0 [1] 0 1 2 (4) 5 1 5 8 9 1 6 7 7 9 2
The Elves think their skill will improve after making a few recipes (your puzzle input). However, that could
take ages; you can speed this up considerably by identifying the scores of the ten recipes after that. For
example:
• If the Elves think their skill will improve after making 9 recipes, the scores of the ten recipes after
the first nine on the scoreboard would be 5158916779 (highlighted in the last line of the diagram).
• After 5 recipes, the scores of the next ten would be 0124515891.
• After 18 recipes, the scores of the next ten would be 9251071085.
• After 2018 recipes, the scores of the next ten would be 5941429882.
What are the scores of the ten recipes immediately after the number of recipes in your puzzle input?
Your puzzle answer was 1776718175.
--- Part Two ---
As it turns out, you got the Elves' plan backwards. They actually want to know how many recipes appear on the
scoreboard to the left of the first recipes whose scores are the digits from your puzzle input.
• 51589 first appears after 9 recipes.
• 01245 first appears after 5 recipes.
• 92510 first appears after 18 recipes.
• 59414 first appears after 2018 recipes.
How many recipes appear on the scoreboard to the left of the score sequence in your puzzle input?
Your puzzle answer was 20220949.
Both parts of this puzzle are complete! They provide two gold stars: **
Your puzzle input was 290431.
References
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