day 23

Author: Oscar Franzén

digidis-go/day23/day23.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	part1, _ := run(parse("input.txt"))
+	fmt.Printf("Part 1: %v\n", part1)
+	fmt.Printf("Part 2 (go): %v\n", part2())
+
+	// asm code using the missing div instructions (mod is not needed)
+	_, part2 := run(parse("input2.txt"))
+	fmt.Printf("Part 2 (asm): %v\n", part2)
+
+}
+
+func parse(file string) (code [][]string) {
+	data, _ := ioutil.ReadFile(file)
+	rows := strings.Split(string(data), "\n")
+	for _, r := range rows {
+		code = append(code, strings.Fields(r))
+	}
+	return
+}
+
+func run(code [][]string) (int, int) {
+	registers := make(map[string]int)
+	var pos, mul int
+	for pos >= 0 && pos < len(code) {
+		op := code[pos]
+		switch op[0] {
+		case "set":
+			registers[op[1]] = get(registers, op[2])
+		case "sub":
+			registers[op[1]] = registers[op[1]] - get(registers, op[2])
+		case "div":
+			registers[op[1]] = registers[op[1]] / get(registers, op[2])
+		case "mul":
+			registers[op[1]] = registers[op[1]] * get(registers, op[2])
+			mul++
+		case "jnz":
+			if get(registers, op[1]) != 0 {
+				pos += get(registers, op[2])
+				continue
+			}
+		default:
+			panic("bad instruciton")
+		}
+		pos++
+	}
+	return mul, registers["h"]
+}
+
+func get(registers map[string]int, r string) int {
+	i, err := strconv.Atoi(r)
+	if err == nil {
+		return i
+	}
+	return registers[r]
+}
+
+// go version of part 2
+func part2() (h int) {
+	for b := 108400; b <= 125400; b += 17 {
+		for d := 2; d < b/2; d++ {
+			if b%d == 0 {
+				h++
+				break
+			}
+		}
+	}
+	return h
+}

digidis-go/day23/input.txt

@@ -0,0 +1,32 @@
+set b 84
+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 2
+jnz 1 3
+sub b -17
+jnz 1 -23

digidis-go/day23/input2.txt

@@ -0,0 +1,21 @@
+set b 108400
+set c 125400
+set d 2
+set g b
+div g d
+mul g d
+sub g b
+jnz g 3
+sub h -1
+jnz 1 6
+sub d -1
+set g b
+div g 2
+sub g d
+jnz g -11
+set g b
+sub g c
+jnz g 2
+jnz 1 3
+sub b -17
+jnz 1 -18