diff --git a/2017/day21/day21.go b/2017/day21/day21.go
index 1c6c70b..4cbd12d 100644
--- a/2017/day21/day21.go
+++ b/2017/day21/day21.go
@@ -3,296 +3,108 @@ package main
 import (
 	"bufio"
 	"fmt"
-	"log"
 	"math"
 	"os"
 	"strings"
-	"time"
 )
 
-var allRules []Rule
+var rules map[string]string
 
 func main() {
+	rules = make(map[string]string)
+
 	inp := StdinToStrings()
 	for i := range inp {
-		allRules = append(allRules, Rule(inp[i]))
+		pts := strings.Split(inp[i], " ")
+		rules[pts[0]] = pts[2]
+		rules[Flip(pts[0])] = pts[2]
+		rules[Rotate(pts[0], 90)] = pts[2]
+		rules[Rotate(pts[0], 180)] = pts[2]
+		rules[Rotate(pts[0], 270)] = pts[2]
 	}
-	//pattern := Pattern(".#./..#/###")
-	pattern := Pattern("../##")
-	fmt.Println(pattern)
-	if !pattern.IsValid() {
-		fmt.Println("Invalid Pattern Given. Must be square.")
-	}
-	ClearScreen()
-	pattern.PrettyPrint()
-	time.Sleep(time.Second)
-	for iters := 0; iters < 5; iters++ {
-		ClearScreen()
-		pattern = Tick(pattern)
-		pattern.PrettyPrint()
-		time.Sleep(time.Second)
-	}
-	fmt.Println("On:", pattern.GetOnCount())
-}
 
-// Stitch takes a slice of patterns and turns them into one large (square) pattern
-func Stitch(inp []Pattern) Pattern {
-	ppr := int(math.Sqrt(float64(len(inp))))
-	newSize := ppr * inp[0].Size()
-	var currRow int
-	rows := make(map[int]string)
-	for i := 0; i < len(inp); i++ {
-		currRow = (i / ppr) * 2
-		for j := 0; j < len(inp[0]); j++ {
-			if len(rows[currRow+j]) == newSize {
-				rows[currRow+j] += "/"
-			}
-			rows[currRow+j] += inp[i].GetRow(j)
+	pattern := ".#./..#/###"
+	for i := 0; i < 2; i++ {
+		Tick(pattern)
+	}
+	/*
+		pattern = rules[pattern]
+		pts := SplitBlocks(pattern)
+		for i := range pts {
+			pts[i] = rules[pts[i]]
 		}
-	}
-	var lines []string
-	for i := 0; i < newSize; i++ {
-		lines = append(lines, rows[i])
-	}
-
-	return Pattern(strings.Join(lines, "/"))
+		fmt.Println(pts)
+		fmt.Println(CombineBlocks(pts))
+	*/
 }
 
-// Run the pattern, or all of it's subpatterns
-// through the rules and return the new pattern
-func Tick(inp Pattern) Pattern {
-	if inp.SubpatternCount() > 1 {
-		var subs []Pattern
-		// Tick each subpattern
-		for i := 0; i < inp.SubpatternCount(); i++ {
-			if s := inp.GetSubpattern(i); s.IsValid() {
-				subs = append(subs, Tick(s))
-			} else {
-				log.Fatal("Error ticking pattern")
-			}
+func Tick(pt string) string {
+	fmt.Println(SplitBlocks(pt))
+	return ""
+}
+
+func SplitBlocks(pt string) []string {
+	var ret []string
+	pts := strings.Split(pt, "/")
+	if len(pts[0]) <= 3 {
+		return []string{pt}
+	}
+	// Assume 3x3
+	blkSize := 3
+	if len(pts[0])%2 == 0 {
+		// 2x2 blocks
+		blkSize = 2
+	}
+	for j := 0; j < len(pts); j += blkSize {
+		for i := 0; i < len(pts[j]); i += blkSize {
+			ret = append(ret, pts[j][i:i+blkSize]+"/"+pts[j+1][i:i+blkSize])
 		}
-		return Stitch(subs)
-	}
-
-	var foundMatch bool
-	for i := range allRules {
-		if allRules[i].Matches(inp) {
-			inp = allRules[i].Output()
-			foundMatch = true
-		}
-	}
-	if !foundMatch {
-		fmt.Println("~ ERROR TICKING ~")
-		inp.PrettyPrint()
-		fmt.Println("~ ERROR TICKING ~")
-		os.Exit(1)
-	}
-	return inp
-}
-
-/**
- * A pattern is a string with some special methods
- */
-type Pattern string
-
-// Print a pattern prettily. (in a square)
-func (p Pattern) PrettyPrint() {
-	pts := strings.Split(string(p), "/")
-	for i := range pts {
-		fmt.Println(pts[i])
-	}
-}
-
-func (p Pattern) GetOnCount() int {
-	return strings.Count(string(p), "#")
-}
-
-// Returns if a pattern is valid.
-// A pattern is valid if it has more than 0 rows
-// and every row is the same length as the number
-// of columns
-func (p Pattern) IsValid() bool {
-	pts := strings.Split(string(p), "/")
-	if len(pts) == 0 {
-		return false
-	}
-	for i := range pts {
-		if len(pts[i]) != len(pts) {
-			return false
-		}
-	}
-	return true
-}
-
-// Returns the "size" of the pattern
-// That is, how many rows/columns it has
-func (p Pattern) Size() int {
-	return len(strings.Split(string(p), "/"))
-}
-
-// Flip returns a new pattern that has been flipped horizontally
-func (p Pattern) Flip() Pattern {
-	// We can only flip the smallest patterns (2x2 or 3x3)
-	if p.SubpatternCount() != 1 {
-		return p
-	}
-	pts := strings.Split(string(p), "/")
-	for i := range pts {
-		pts[i] = RevString(pts[i])
-	}
-	return Pattern(strings.Join(pts, "/"))
-}
-
-// Rotate returns a new pattern that has been rotated deg degrees
-// Only right-angles
-func (p Pattern) Rotate(deg int) Pattern {
-	// We can only rotate the smallest patterns (2x2 or 3x3)
-	if p.SubpatternCount() != 1 {
-		return p
-	}
-
-	if deg < 0 {
-		deg += 360
-	} else if deg == 0 {
-		return p
-	}
-
-	pts := strings.Split(string(p), "/")
-	ret := make([]string, len(pts))
-	use := p
-	switch deg {
-	case 90:
-		if p.Size()%3 == 0 {
-			ret[0] = RevString(use.GetCol(2))
-			ret[1] = RevString(use.GetCol(1))
-			ret[2] = RevString(use.GetCol(0))
-		} else {
-			ret[0] = RevString(use.GetCol(1))
-			ret[1] = RevString(use.GetCol(0))
-		}
-	case 180:
-		if p.Size()%3 == 0 {
-			ret[0] = RevString(use.GetRow(2))
-			ret[1] = RevString(use.GetRow(1))
-			ret[2] = RevString(use.GetRow(0))
-		} else {
-			ret[0] = RevString(use.GetRow(1))
-			ret[1] = RevString(use.GetRow(0))
-		}
-	case 270:
-		if p.Size()%3 == 0 {
-			ret[0] = use.GetCol(2)
-			ret[1] = use.GetCol(1)
-			ret[2] = use.GetCol(0)
-		} else {
-			ret[0] = use.GetCol(1)
-			ret[1] = use.GetCol(0)
-		}
-
-	}
-	use = Pattern(strings.Join(ret, "/"))
-	return Pattern(strings.Join(ret, "/"))
-}
-
-// GetRow returns a row as a string
-func (p Pattern) GetRow(row int) string {
-	pts := strings.Split(string(p), "/")
-	if row >= len(pts) {
-		return ""
-	}
-	return pts[row]
-}
-
-// GetCol returns a column as a string
-func (p Pattern) GetCol(col int) string {
-	var ret string
-	pts := strings.Split(string(p), "/")
-	if col >= len(pts[0]) {
-		return ""
-	}
-	for i := 0; i < len(pts); i++ {
-		ret = ret + string(pts[i][col])
 	}
 	return ret
 }
 
-// Counts the number of subpatterns in the pattern
-func (p Pattern) SubpatternCount() int {
-	if p.Size()%2 == 0 {
-		return (p.Size() / 2) * (p.Size() / 2)
-	} else {
-		return (p.Size() / 3) * (p.Size() / 3)
+func CombineBlocks(pts []string) string {
+	var ret string
+	sz := int(math.Sqrt(float64(len(pts))))
+	fmt.Println("Combining")
+	fmt.Println(sz)
+	//var j int
+	for i := 0; i < len(pts); i++ {
 	}
+	return ret
 }
 
-// Gets a specific subpattern out of the pattern
-func (p Pattern) GetSubpattern(i int) Pattern {
-	if i > p.SubpatternCount() {
-		return Pattern("")
+func Flip(pt string) string {
+	pts := strings.Split(pt, "/")
+	var newPts []string
+	for i := range pts {
+		newPts = append(newPts, RevString(pts[i]))
 	}
-	subSize := 3 // Assume 3x3 subpatterns
-	if p.Size()%2 == 0 {
-		// Subpatterns are actually 2x2
-		subSize = 2
+	return strings.Join(newPts, "/")
+}
+
+func Rotate(pt string, deg int) string {
+	if deg == 0 {
+		return pt
 	}
-	ppr := p.Size() / subSize
-	col := i % (p.Size() / subSize)
-	row := i / ppr
-	ptString := ""
-	for j := 0; j < subSize; j++ {
-		ptString += p.GetRow((row * 2) + j)[(col*subSize):(col*subSize)+subSize] + "/"
+	if deg%90 != 0 {
+		// We can't do this
+		fmt.Println("Invalid Rotation:", deg)
+		os.Exit(1)
 	}
-	return Pattern(ptString[:len(ptString)-1])
-}
-
-/**
- * Rule is an interface that can take a pattern and return if it matches,
- * report on it's size, or return the resulting pattern from applying itself
- * to a pattern
- */
-type RuleFace interface {
-	Matches(inp Pattern) bool
-	InputSize() int
-	Apply(inp Pattern) Pattern
-}
-
-/**
- * Rule implements the RuleFace interface
- * for 2x2 => 3x3 transitions
- * or 3x3 => 4x4 transitions
- */
-type Rule string
-
-func (r Rule) Input() Pattern {
-	pts := strings.Split(string(r), " ")
-	return Pattern(pts[0])
-}
-
-func (r Rule) Output() Pattern {
-	pts := strings.Split(string(r), " ")
-	return Pattern(pts[2])
-}
-
-func (r Rule) Matches(inp Pattern) bool {
-	if inp.Size() != r.InputSize() {
-		return false
+	pts := strings.Split(pt, "/")
+	var tst string
+	if len(pts[0])%2 == 0 {
+		// 2x2 pattern
+		tst = string(pts[1][0]) + string(pts[0][0]) + "/"
+		tst += string(pts[1][1]) + string(pts[0][1])
+		return Rotate(tst, deg-90)
 	}
-	// Try it rotated 90,180,270
-	for i := 0; i < 360; i += 90 {
-		if r.Equals(inp.Rotate(i)) || r.Equals(inp.Flip().Rotate(i)) {
-			return true
-		}
-	}
-	return false
-}
-
-func (r Rule) InputSize() int {
-	return len(strings.Split(string(r.Input()), "/"))
-}
-
-// Equals is a direct string comparison
-func (r Rule) Equals(inp Pattern) bool {
-	return string(r.Input()) == string(inp)
+	// 3x3 pattern
+	tst = string(pts[2][0]) + string(pts[1][0]) + string(pts[0][0]) + "/"
+	tst += string(pts[2][1]) + string(pts[1][1]) + string(pts[0][1]) + "/"
+	tst += string(pts[2][2]) + string(pts[1][2]) + string(pts[0][2])
+	return Rotate(tst, deg-90)
 }
 
 func RevString(s string) string {
@@ -303,10 +115,6 @@ func RevString(s string) string {
 	return string(runes)
 }
 
-func ClearScreen() {
-	fmt.Println("\033[H\033[2J")
-}
-
 func StdinToStrings() []string {
 	var input []string
 	scanner := bufio.NewScanner(os.Stdin)
diff --git a/2017/day23/.gitignore b/2017/day23/.gitignore
new file mode 100644
index 0000000..523a316
--- /dev/null
+++ b/2017/day23/.gitignore
@@ -0,0 +1,3 @@
+day23-part2
+day23-part1
+test
diff --git a/2017/day23/day23-part1.go b/2017/day23/day23-part1.go
new file mode 100644
index 0000000..9f72fbe
--- /dev/null
+++ b/2017/day23/day23-part1.go
@@ -0,0 +1,116 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	inp := StdinToStrings()
+	run(inp)
+}
+
+var reg map[string]int
+
+func run(inp []string) {
+	reg = make(map[string]int)
+	reg["a"] = 1
+	var mulCount int
+
+	var instCnt int
+	for i := 0; i >= 0 && i < len(inp); i++ {
+		instCnt++
+		if instCnt%10 == 0 {
+			ClearScreen()
+			printInstructions(inp, i)
+		}
+		pts := strings.Split(inp[i], " ")
+		if pts[1] == "h" || pts[2] == "h" {
+			fmt.Println("Hit h")
+		}
+		switch pts[0] {
+		case "set":
+			setReg(pts[1], pts[2])
+		case "sub":
+			subReg(pts[1], pts[2])
+		case "mul":
+			mulCount++
+			mulReg(pts[1], pts[2])
+		case "jnz":
+			i += jumpNotZero(pts[1], pts[2])
+		}
+	}
+
+	fmt.Println("Result (H):", reg["h"])
+}
+
+func setReg(key string, val string) {
+	reg[key] = getValue(val)
+}
+
+func subReg(key string, val string) {
+	reg[key] = getValue(key) - getValue(val)
+}
+
+func mulReg(key string, val string) {
+	reg[key] = getValue(key) * getValue(val)
+}
+
+func jumpNotZero(test string, jump string) int {
+	var ret int
+	if getValue(test) != 0 {
+		ret = getValue(jump) - 1
+	}
+	return ret
+}
+
+func getValue(key string) int {
+	var ret int
+	var ok bool
+	var err error
+	if ret, err = strconv.Atoi(key); err != nil {
+		// It's not a number
+		if ret, ok = reg[key]; !ok {
+			// The register is empty
+			reg[key] = 0
+			ret = 0
+		}
+	}
+	return ret
+}
+
+func PrintRegisters() {
+	fmt.Print("[ ")
+	for i := 0; i < 26; i++ {
+		getReg := string('a' + i)
+		fmt.Printf("%s:%d ", getReg, getValue(getReg))
+	}
+	fmt.Print("]\n")
+}
+
+func printInstructions(inp []string, pos int) {
+	PrintRegisters()
+	for i := range inp {
+		if i == pos {
+			fmt.Print("> ", inp[i], "\n")
+		} else {
+			fmt.Print("  ", inp[i], "\n")
+		}
+	}
+}
+
+func ClearScreen() {
+	fmt.Print("\033[H\033[2J")
+}
+
+func StdinToStrings() []string {
+	var input []string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = append(input, scanner.Text())
+	}
+	return input
+}
diff --git a/2017/day23/day23-part2.go b/2017/day23/day23-part2.go
new file mode 100644
index 0000000..88e0600
--- /dev/null
+++ b/2017/day23/day23-part2.go
@@ -0,0 +1,54 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+func main() {
+	var a, b, c, d, e, f, g, h int
+	// Suppress go warnings
+	_, _, _, _, _, _, _, _ = a, b, c, d, e, f, g, h
+	// Derived from test.go
+	b = 109900
+	c = 126900
+
+	// Unoptimized:
+	/*
+		for ; b < c+1; b += 17 {
+			f = 1
+			for d = 2; d < b+1; d++ {
+				for e = 2; e < b+1; e++ {
+					if d*e == b {
+						f = 0
+					}
+				}
+			}
+			// When is f 0?
+			// when d*e == b for "certain values" of b
+			fmt.Println(d, e, b)
+			if f == 0 {
+				h++
+			}
+			// b = 109900
+		}
+	*/
+
+	// Optimized
+	for ; b < c+1; b += 17 {
+		if !IsPrime(b) {
+			h++
+		}
+	}
+
+	fmt.Println(h)
+}
+
+func IsPrime(value int) bool {
+	for i := 2; i <= int(math.Floor(float64(value)/2)); i++ {
+		if value%i == 0 {
+			return false
+		}
+	}
+	return value > 1
+}
diff --git a/2017/day23/input b/2017/day23/input
new file mode 100644
index 0000000..9b73642
--- /dev/null
+++ b/2017/day23/input
@@ -0,0 +1,32 @@
+set b 99
+set c b
+jnz a 2
+jnz 1 5
+mul b 100
+sub b -100000
+set c b
+sub c -17000
+set f 1
+set d 2
+set e 2
+set g d
+mul g e
+sub g b
+jnz g 2
+set f 0
+sub e -1
+set g e
+sub g b
+jnz g -8
+sub d -1
+set g d
+sub g b
+jnz g -13
+jnz f 2
+sub h -1
+set g b
+sub g c
+jnz g 0
+jnz 1 3
+sub b -17
+jnz 1 -23
diff --git a/2017/day23/input-disassemble b/2017/day23/input-disassemble
new file mode 100644
index 0000000..825fab6
--- /dev/null
+++ b/2017/day23/input-disassemble
@@ -0,0 +1,52 @@
+b = 99
+c = b
+if a != 0 {
+  b = b * 100
+  b = b + 100000
+  c = b
+  c = c + 17000
+}
+// b = 109900
+// c = 126900
+
+for {
+  f = 1
+  d = 2
+  for {
+    e = 2
+    g = d
+    for {
+      g = g * e
+      g = g - b
+
+      if g == 0 {
+        f = 0
+      }
+
+      e = e + 1
+      g = e
+      g = g - b
+      if g != 0 {
+        break
+      }
+    }
+
+    d = d + 1
+    g = d
+    g = g - b
+    if g != 0 {
+      break
+    }
+  }
+  if f == 0 {
+    h = h + 1
+  }
+  g = b
+  g = g - c
+
+  if g == 0 {
+    break
+  }
+  b = b + 17
+}
+
diff --git a/2017/day23/input-loops b/2017/day23/input-loops
new file mode 100644
index 0000000..82fff08
--- /dev/null
+++ b/2017/day23/input-loops
@@ -0,0 +1,39 @@
+set b 99
+set c b
+
+jnz a 2
+jnz 1 5
+mul b 100
+sub b -100000
+set c b
+sub c -17000
+
+  set f 1
+  set d 2
+    set e 2
+    set g d
+      mul g e
+      sub g b
+
+      jnz g 2
+      set f 0
+
+      sub e -1
+      set g e
+      sub g b
+      jnz g -8
+    sub d -1
+    set g d
+    sub g b
+    jnz g -13
+
+  jnz f 2
+  sub h -1
+
+  set g b
+  sub g c
+
+  jnz g 0
+  jnz 1 3
+  sub b -17
+  jnz 1 -23
diff --git a/2017/day23/test.go b/2017/day23/test.go
new file mode 100644
index 0000000..51ba6c9
--- /dev/null
+++ b/2017/day23/test.go
@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+// Logic before any loops (starting values)
+func main() {
+	var a, b, c int
+	b = 99
+	c = b
+	b = b * 100
+	b = b + 100000
+	c = b
+	c = c + 17000
+	fmt.Println(a, b, c)
+}