From 50254aa2c13e89766ff880fb9b96145771a31e01 Mon Sep 17 00:00:00 2001
From: Brian Buller <brbuller@gmail.com>
Date: Sun, 16 Dec 2018 06:25:50 +0000
Subject: [PATCH] 2018 Day 22 Part 1 Done

---
 2018/day22/day22.go  | 155 +++++++++++++++++++++++++++++++++++++++++++
 2018/day22/input     |   2 +
 2018/day22/testinput |   2 +
 3 files changed, 159 insertions(+)
 create mode 100644 2018/day22/day22.go
 create mode 100644 2018/day22/input
 create mode 100644 2018/day22/testinput

diff --git a/2018/day22/day22.go b/2018/day22/day22.go
new file mode 100644
index 0000000..e60d206
--- /dev/null
+++ b/2018/day22/day22.go
@@ -0,0 +1,155 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var depth int
+var target *Pos
+
+func main() {
+	input := stdinToStringSlice()
+	reg, err := regexp.Compile("[^0-9]+")
+	if err != nil {
+		log.Fatal(err)
+	}
+	depth = Atoi(reg.ReplaceAllString(input[0], ""))
+	tgt := strings.Trim(input[1], "target: ")
+	tgtPts := strings.Split(tgt, ",")
+	target = NewPos(Atoi(tgtPts[0]), Atoi(tgtPts[1]), depth)
+
+}
+
+func part1() {
+	c := BuildCave(target)
+	var risk int
+	for y := 0; y <= target.y; y++ {
+		for x := 0; x <= target.x; x++ {
+			risk += c.risk(x, y, depth)
+		}
+	}
+	fmt.Println("= Part 1 =")
+	fmt.Println(risk)
+}
+
+func part2() {
+	// Find shortest path form 0,0 to target
+	// taking into account cost of changing gear
+	// when necessary
+
+}
+
+type Cave struct {
+	positions map[string]*Pos
+}
+
+func BuildCave(target *Pos) *Cave {
+	c := &Cave{
+		positions: make(map[string]*Pos),
+	}
+	c.addPos(target)
+	return c
+}
+
+func (c *Cave) addPos(p *Pos) {
+	c.positions[p.string()] = p
+}
+
+func (c *Cave) getPos(x, y, z int) *Pos {
+	var p *Pos
+	var ok bool
+	if p, ok = c.positions[c.buildKey(x, y, z)]; !ok {
+		p = NewPos(x, y, z)
+		c.addPos(p)
+	}
+	return p
+}
+
+func (c *Cave) buildKey(x, y, z int) string {
+	return fmt.Sprintf(
+		"(%d,%d,%d)",
+		x, y, z,
+	)
+}
+
+func (c *Cave) getGeoIndex(x, y, z int) int {
+	p := c.getPos(x, y, z)
+	if p.geo < 0 {
+		if x == 0 && y == 0 {
+			p.geo = 0
+		} else if x == target.x && y == target.y {
+			p.geo = 0
+		} else if y == 0 {
+			p.geo = x * 16807
+		} else if x == 0 {
+			p.geo = y * 48271
+		} else {
+			p.geo = c.erosion(x-1, y, z) * c.erosion(x, y-1, z)
+		}
+	}
+	return p.geo
+}
+
+func (c *Cave) erosion(x, y, z int) int {
+	p := c.getPos(x, y, z)
+	if p.erosion < 0 {
+		p.erosion = (c.getGeoIndex(x, y, z) + z) % 20183
+	}
+	return p.erosion
+}
+
+func (c *Cave) risk(x, y, z int) int {
+	return c.erosion(x, y, z) % 3
+}
+
+type Pos struct {
+	x, y, z      int
+	geo, erosion int
+}
+
+func NewPos(x, y, z int) *Pos {
+	r := &Pos{
+		x:       x,
+		y:       y,
+		z:       z,
+		geo:     -1,
+		erosion: -1,
+	}
+
+	return r
+}
+
+func (p *Pos) equals(n *Pos) bool {
+	return p.x == n.x && p.y == n.y && p.z == n.z
+}
+
+func (p *Pos) string() string {
+	return fmt.Sprintf(
+		"(%d,%d,%d)",
+		p.x, p.y, p.z,
+	)
+}
+
+func stdinToStringSlice() []string {
+	var input []string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = append(input, scanner.Text())
+	}
+	return input
+}
+
+func Atoi(i string) int {
+	var ret int
+	var err error
+	if ret, err = strconv.Atoi(i); err != nil {
+		log.Fatal("Invalid Atoi: " + i)
+	}
+	return ret
+}
diff --git a/2018/day22/input b/2018/day22/input
new file mode 100644
index 0000000..b08bfa0
--- /dev/null
+++ b/2018/day22/input
@@ -0,0 +1,2 @@
+depth: 6084
+target: 14,709
diff --git a/2018/day22/testinput b/2018/day22/testinput
new file mode 100644
index 0000000..eea8c66
--- /dev/null
+++ b/2018/day22/testinput
@@ -0,0 +1,2 @@
+depth: 510
+target: 10,10