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2020 Day 23 Complete!

master
Brian Buller 10 months ago
parent
commit
3b5bae7948
  1. 1
      2020/day23/input
  2. 228
      2020/day23/main.go
  3. 1
      2020/day23/testinput

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2020/day23/input

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614752839

228
2020/day23/main.go

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package main
import (
"fmt"
h "git.bullercodeworks.com/brian/adventofcode/helpers"
)
var highest int
var lowest int
var AllCups map[int]*Cup
func init() {
highest = h.MIN_INT
lowest = h.MAX_INT
AllCups = make(map[int]*Cup)
}
func main() {
fmt.Println("# Day 22")
inp := h.StdinToString()
solve(inp, h.Atoi(h.OptArgNumber(1, "2")))
}
var move int
var first *Cup
func solve(inp string, part int) {
moves := 100
if part == 1 {
BuildCircle(inp, -1)
} else {
BuildCircle(inp, 1000000)
moves = 10000000
}
current := first
for i := 0; i < moves; i++ {
current = DoMove(current)
}
ans := FindLabel(1, first).next
fmt.Println("## Part", part, ":\nAnswer:")
if part == 1 {
for ans.label != 1 {
fmt.Print(ans.label)
ans = ans.next
}
} else {
fmt.Print(ans.label * ans.next.label)
}
fmt.Println()
}
func BuildCircle(inp string, cups int) *Cup {
var wrk *Cup
for k := range inp {
next := &Cup{label: int(inp[k] - '0')}
next.next = next
next.prev = next
if first == nil {
first = next
first.next = next
first.prev = next
} else {
wrk.SetNext(next)
}
if next.label > highest {
highest = next.label
}
if next.label < lowest {
lowest = next.label
}
AllCups[next.label] = next
wrk = next
}
total := Count(first)
last := GetLast(first)
nextLabel := highest + 1
for cups > 0 && total < cups {
next := &Cup{label: nextLabel}
nextLabel++
next.next = next
next.prev = next
last.SetNext(next)
last = next
if next.label > highest {
highest = next.label
}
if next.label < lowest {
lowest = next.label
}
AllCups[next.label] = next
total++
}
return first
}
func DoMove(curr *Cup) *Cup {
move++
hold := curr.RemoveNext(3)
target := curr.label - 1
if target < lowest {
target = highest
}
// Check the removed cups
for FindLabel(target, hold) != nil {
target = target - 1
if target < lowest {
target = highest
}
}
//dest := FindLabel(target, curr)
dest := AllCups[target]
dest.SetNext(hold)
return curr.next
}
func FindLabel(num int, first *Cup) *Cup {
if first.label == num {
return first
}
c := first.next
for c != first {
if c.label == num {
return c
}
c = c.next
}
return nil
}
func StringifyCircle(first *Cup, current *Cup) string {
c := first
stringify := func(c *Cup) string {
if c == nil {
return "ERR"
}
if c == current {
return fmt.Sprintf("(%d)", c.label)
} else {
return fmt.Sprintf(" %d ", c.label)
}
}
ret := stringify(c)
c = c.next
for c != first {
ret = ret + stringify(c)
if c == nil {
ret = ret + " ERR "
break
}
if c.next == c {
break
}
c = c.next
}
return ret
}
func GetLast(cups *Cup) *Cup {
if cups.next == cups || cups.next == nil {
return cups
}
c := cups.next
for c.next != cups {
if c.next == nil {
break
}
c = c.next
}
return c
}
func Count(cups *Cup) int {
start := cups
wrk := start.next
ret := 1
for wrk != start {
wrk = wrk.next
ret++
}
return ret
}
var current *Cup
type Cup struct {
label int
next *Cup
prev *Cup
}
func (c *Cup) SetNext(next *Cup) {
if c.next == c {
c.prev = next
c.next = next
next.next = c
next.prev = c
return
}
hold := c.next
// c.p c c.n
// c.p c next... c.n
c.next = next
if hold != nil {
hold.prev = GetLast(next)
GetLast(next).next = hold
}
next.prev = c
}
// RemoveNext removes the next cnt cups, returning a circle of the removed cups
func (c *Cup) RemoveNext(cnt int) *Cup {
if cnt == 0 {
return nil
}
hold := c.next
dest := hold
for cnt > 0 {
dest = dest.next
cnt--
}
c.next = dest
dest.prev.next = hold
hold.prev = dest.prev
dest.prev = c
return hold
}

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2020/day23/testinput

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