From 18d07e81db33bb0a4262a46e6807d432540b8b7e Mon Sep 17 00:00:00 2001
From: Brian Buller <brbuller@gmail.com>
Date: Wed, 12 Dec 2018 16:55:33 -0600
Subject: [PATCH] 2018 day 12 done

---
 2018/day12/day12.go | 273 +++++++++++++++++++++++++++++---------------
 2018/day12/problem  | 123 ++++++++++++++++++++
 2 files changed, 304 insertions(+), 92 deletions(-)
 create mode 100644 2018/day12/problem

diff --git a/2018/day12/day12.go b/2018/day12/day12.go
index f0317c6..c327873 100644
--- a/2018/day12/day12.go
+++ b/2018/day12/day12.go
@@ -7,136 +7,177 @@ import (
 	"strings"
 )
 
-var row map[int]bool
-var transitions []*Transition
+const (
+	MaxInt = int(^uint(0) >> 1)
+	MinInt = -MaxInt - 1
+)
+
+var lastState string
+var garden *Garden
 
 func main() {
 	inp := StdinToStringSlice()
-	BuildRow(inp[0])
+	garden = NewGarden(strings.Trim(inp[0], "intalsae: "), 0)
 	for _, v := range inp[2:] {
-		transitions = append(transitions, NewTransition(v))
+		garden.transitions = append(garden.transitions, NewTransition(v))
 	}
-	fmt.Print("St: ")
-	PrintState()
-	for i := 0; i < 20; i++ {
-		Tick()
-		fmt.Printf("%2d: ", i)
-		PrintState()
+	generations := 50000000000
+	var i int
+	for i = 0; i < generations; i++ {
+		lastState = garden.string()
+		garden = garden.tick()
+		if garden.string() == lastState {
+			i++
+			break
+		}
 	}
-	fmt.Println("Total:", GetSum())
+	garden.shiftPots(generations - i)
+	fmt.Println(garden.sum())
 }
 
-func Tick() {
-	m := make(map[int]bool)
-	lowest, highest := 0, 0
-	for i := range row {
-		if i < lowest {
-			lowest = i
-		}
-		if i > highest {
-			highest = i
+/**
+ * A Garden
+ */
+type Garden struct {
+	pots        []*Pot
+	transitions []*Transition
+}
+
+func NewGarden(inp string, start int) *Garden {
+	g := &Garden{}
+	for k, v := range inp {
+		p := &Pot{
+			id:    k + start,
+			value: rb(v),
 		}
+		g.pots = append(g.pots, p)
 	}
-	for i := lowest - 2; i <= highest+2; i++ {
-		m[i] = GetNextValue(i)
-	}
-	lowest, highest = 0, 0
-	for k := range m {
-		if k < lowest && m[k] {
-			lowest = k
-		}
-		if k > highest && m[k] {
-			highest = k
-		}
-	}
-	row = make(map[int]bool)
-	for i := lowest; i <= highest; i++ {
-		row[i] = m[i]
+	return g
+}
+
+func (g *Garden) shiftPots(val int) {
+	for i := range g.pots {
+		g.pots[i].id = g.pots[i].id + val
 	}
 }
 
-func GetSum() int {
-	var ret int
-	lowest, highest := 0, 0
-	for i := range row {
-		if i < lowest {
-			lowest = i
-		}
-		if i > highest {
-			highest = i
-		}
-	}
-	for i := lowest; i <= highest; i++ {
-		if row[i] {
-			ret += i
+func (g *Garden) sum() int64 {
+	var ret int64
+	st, ed := g.getStartIndex(), g.getEndIndex()
+	for i := st; i <= ed; i++ {
+		if g.getPot(i).value {
+			ret += int64(i)
 		}
 	}
 	return ret
 }
 
-func BuildRow(inp string) {
-	inp = strings.Split(inp, ": ")[1]
-	row = make(map[int]bool)
-	for i, v := range inp {
-		row[i] = rb(v)
+func (g *Garden) tick() *Garden {
+	earliest, latest := g.getStartIndex(), g.getEndIndex()
+	st := earliest - 2
+	ed := latest + 2
+	ret := &Garden{
+		transitions: g.transitions,
 	}
+	for i := st; i <= ed; i++ {
+		next := g.getNextStateForPot(i)
+		if next {
+			ret.pots = append(ret.pots, &Pot{
+				id:    i,
+				value: next,
+			})
+		}
+	}
+	return ret
 }
 
-func GetIdxValue(idx int) byte {
+func (g *Garden) getNextStateForPot(id int) bool {
 	var ret byte
-	for i := idx + 2; i >= idx-2; i-- {
+	for i := id - 2; i <= id+2; i++ {
 		ret = ret << 1
-		if row[i] {
+		if g.getPot(i).value {
 			ret = ret | 1
 		}
 	}
-	return ret
-}
-
-func GetNextValue(idx int) bool {
-	idxVal := GetIdxValue(idx)
-	for _, v := range transitions {
-		if v.GetValue() == idxVal {
+	for _, v := range g.transitions {
+		if v.GetValue() == ret {
 			return v.next
 		}
 	}
-	return false
+	return false //g.getPot(id).value
 }
 
-func GetValueString(b byte) string {
+func (g *Garden) substring(st, ed int) string {
 	var ret string
-	for i := 0; i < 5; i++ {
-		if (b & 1) == 1 {
-			ret = ret + "#"
-		} else {
-			ret = ret + "."
-		}
-		b = b >> 1
+	for i := st; i <= ed; i++ {
+		ret += g.getPot(i).string()
 	}
 	return ret
 }
 
-func PrintState() {
-	lowest, highest := -2, 30
-	for i := range row {
-		if i < lowest {
-			lowest = i
-		}
-		if i > highest {
-			highest = i
-		}
+func (g *Garden) string() string {
+	var ret string
+	for i := g.getStartIndex(); i <= g.getEndIndex(); i++ {
+		ret += g.getPot(i).string()
 	}
-	fmt.Print("(", lowest, ") ")
-	for i := lowest; i <= highest; i++ {
-		if row[i] {
-			fmt.Print("#")
-		} else {
-			fmt.Print(".")
-		}
-	}
-	fmt.Println(" (", highest, ") ")
+	return ret
 }
 
+func (g *Garden) transitionStrings() string {
+	var ret string
+	for _, v := range g.transitions {
+		ret = ret + v.string() + "\n"
+	}
+	return ret
+}
+
+func (g *Garden) getStartIndex() int {
+	min := MaxInt
+	for _, v := range g.pots {
+		if v.id < min {
+			min = v.id
+		}
+	}
+	return min
+}
+
+func (g *Garden) getEndIndex() int {
+	max := MinInt
+	for _, v := range g.pots {
+		if v.id > max {
+			max = v.id
+		}
+	}
+	return max
+}
+
+func (g *Garden) getPot(idx int) *Pot {
+	for _, v := range g.pots {
+		if v.id == idx {
+			return v
+		}
+	}
+	return &Pot{
+		id:    idx,
+		value: false,
+	}
+}
+
+/**
+ * A Pot
+ */
+type Pot struct {
+	id    int
+	value bool
+}
+
+func (p *Pot) string() string {
+	return bs(p.value)
+}
+
+/**
+ * Transitions
+ */
 type Transition struct {
 	state []bool
 	next  bool
@@ -146,9 +187,12 @@ func NewTransition(inp string) *Transition {
 	var state []bool
 	var next bool
 	pts := strings.Split(inp, " => ")
-	for i := len(pts[0]) - 1; i >= 0; i-- {
+	for i := range pts[0] {
 		state = append(state, bb(pts[0][i]))
 	}
+	//for i := len(pts[0]) - 1; i >= 0; i-- {
+	//	state = append(state, bb(pts[0][i]))
+	//}
 	next = bb(pts[1][0])
 	t := &Transition{
 		state: state,
@@ -157,6 +201,14 @@ func NewTransition(inp string) *Transition {
 	return t
 }
 
+func (t *Transition) string() string {
+	var ret string
+	for _, v := range t.state {
+		ret += bs(v)
+	}
+	return ret + " => " + bs(t.next)
+}
+
 func (t *Transition) GetValue() byte {
 	var ret byte
 	for _, v := range t.state {
@@ -168,6 +220,43 @@ func (t *Transition) GetValue() byte {
 	return ret
 }
 
+/**
+ * Helper Functions
+ */
+
+// Take a byte and return a string representation of the bits
+func byteToString(b byte) string {
+	var ret string
+	for i := 0; i < 8; i++ {
+		if b&1 == 1 {
+			ret += "#"
+		} else {
+			ret += "."
+		}
+		b = b >> 1
+	}
+	return ret
+}
+
+// Take a string representation of a bits and return the byte
+func stringToByte(n string) byte {
+	var b byte
+	for i := range n {
+		if n[i] == '#' {
+			b = b | 1
+		}
+		b = b << 1
+	}
+	return b
+}
+
+func bs(b bool) string {
+	if b {
+		return "#"
+	}
+	return "."
+}
+
 func rb(r rune) bool {
 	return bb(byte(r))
 }
diff --git a/2018/day12/problem b/2018/day12/problem
new file mode 100644
index 0000000..c4c361b
--- /dev/null
+++ b/2018/day12/problem
@@ -0,0 +1,123 @@
+Advent of Code
+
+--- Day 12: Subterranean Sustainability ---
+
+   The year 518 is significantly more underground than your history books implied. Either that, or you've arrived in a vast
+   cavern network under the North Pole.
+
+   After exploring a little, you discover a long tunnel that contains a row of small pots as far as you can see to your left
+   and right. A few of them contain plants - someone is trying to grow things in these geothermally-heated caves.
+
+   The pots are numbered, with 0 in front of you. To the left, the pots are numbered -1, -2, -3, and so on; to the right, 1, 2,
+   3.... Your puzzle input contains a list of pots from 0 to the right and whether they do (#) or do not (.) currently contain
+   a plant, the initial state. (No other pots currently contain plants.) For example, an initial state of #..##.... indicates
+   that pots 0, 3, and 4 currently contain plants.
+
+   Your puzzle input also contains some notes you find on a nearby table: someone has been trying to figure out how these
+   plants spread to nearby pots. Based on the notes, for each generation of plants, a given pot has or does not have a plant
+   based on whether that pot (and the two pots on either side of it) had a plant in the last generation. These are written as
+   LLCRR => N, where L are pots to the left, C is the current pot being considered, R are the pots to the right, and N is
+   whether the current pot will have a plant in the next generation. For example:
+
+     • A note like ..#.. => . means that a pot that contains a plant but with no plants within two pots of it will not have a
+       plant in it during the next generation.
+     • A note like ##.## => . means that an empty pot with two plants on each side of it will remain empty in the next
+       generation.
+     • A note like .##.# => # means that a pot has a plant in a given generation if, in the previous generation, there were
+       plants in that pot, the one immediately to the left, and the one two pots to the right, but not in the ones immediately
+       to the right and two to the left.
+
+   It's not clear what these plants are for, but you're sure it's important, so you'd like to make sure the current
+   configuration of plants is sustainable by determining what will happen after 20 generations.
+
+   For example, given the following input:
+
+ initial state: #..#.#..##......###...###
+
+ ...## => #
+ ..#.. => #
+ .#... => #
+ .#.#. => #
+ .#.## => #
+ .##.. => #
+ .#### => #
+ #.#.# => #
+ #.### => #
+ ##.#. => #
+ ##.## => #
+ ###.. => #
+ ###.# => #
+ ####. => #
+
+   For brevity, in this example, only the combinations which do produce a plant are listed. (Your input includes all possible
+   combinations.) Then, the next 20 generations will look like this:
+
+                  1         2         3
+        0         0         0         0
+  0: ...#..#.#..##......###...###...........
+  1: ...#...#....#.....#..#..#..#...........
+  2: ...##..##...##....#..#..#..##..........
+  3: ..#.#...#..#.#....#..#..#...#..........
+  4: ...#.#..#...#.#...#..#..##..##.........
+  5: ....#...##...#.#..#..#...#...#.........
+  6: ....##.#.#....#...#..##..##..##........
+  7: ...#..###.#...##..#...#...#...#........
+  8: ...#....##.#.#.#..##..##..##..##.......
+  9: ...##..#..#####....#...#...#...#.......
+ 10: ..#.#..#...#.##....##..##..##..##......
+ 11: ...#...##...#.#...#.#...#...#...#......
+ 12: ...##.#.#....#.#...#.#..##..##..##.....
+ 13: ..#..###.#....#.#...#....#...#...#.....
+ 14: ..#....##.#....#.#..##...##..##..##....
+ 15: ..##..#..#.#....#....#..#.#...#...#....
+ 16: .#.#..#...#.#...##...#...#.#..##..##...
+ 17: ..#...##...#.#.#.#...##...#....#...#...
+ 18: ..##.#.#....#####.#.#.#...##...##..##..
+ 19: .#..###.#..#.#.#######.#.#.#..#.#...#..
+ 20: .#....##....#####...#######....#.#..##.
+
+   The generation is shown along the left, where 0 is the initial state. The pot numbers are shown along the top, where 0
+   labels the center pot, negative-numbered pots extend to the left, and positive pots extend toward the right. Remember, the
+   initial state begins at pot 0, which is not the leftmost pot used in this example.
+
+   After one generation, only seven plants remain. The one in pot 0 matched the rule looking for ..#.., the one in pot 4
+   matched the rule looking for .#.#., pot 9 matched .##.., and so on.
+
+   In this example, after 20 generations, the pots shown as # contain plants, the furthest left of which is pot -2, and the
+   furthest right of which is pot 34. Adding up all the numbers of plant-containing pots after the 20th generation produces
+   325.
+
+   After 20 generations, what is the sum of the numbers of all pots which contain a plant?
+
+   Your puzzle answer was 2281.
+
+--- Part Two ---
+
+   You realize that 20 generations aren't enough. After all, these plants will need to last another 1500 years to even reach
+   your timeline, not to mention your future.
+
+   After fifty billion (50000000000) generations, what is the sum of the numbers of all pots which contain a plant?
+
+   Your puzzle answer was 2250000000120.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+References
+
+   Visible links
+   . https://adventofcode.com/
+   . https://adventofcode.com/2018/about
+   . https://adventofcode.com/2018/events
+   . https://adventofcode.com/2018/settings
+   . https://adventofcode.com/2018/auth/logout
+   . Advent of Code Supporter
+	https://adventofcode.com/2018/support
+   . https://adventofcode.com/2018
+   . https://adventofcode.com/2018
+   . https://adventofcode.com/2018/support
+   . https://adventofcode.com/2018/sponsors
+   . https://adventofcode.com/2018/leaderboard
+   . https://adventofcode.com/2018/stats
+   . https://adventofcode.com/2018/sponsors
+   . https://adventofcode.com/2018
+   . https://adventofcode.com/2018/day/12/input