Day 14: Part 1 and 2

Signed-off-by: James Griffin <james@unsupervised.ca>

fourteen/day_fourteen.go

@@ -0,0 +1,199 @@
+package fourteen
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type command struct {
+	mem     int
+	pointer int
+
+	mask   string
+	isMask bool
+}
+
+type computer struct {
+	memory map[int]uint64
+	m      map[int]bool
+
+	mask  string
+	ones  uint64
+	zeros uint64
+
+	input    []command
+	executed bool
+}
+
+func (c *computer) load(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		inputs := strings.Split(scanner.Text(), " = ")
+		if len(inputs) != 2 {
+			return fmt.Errorf("Unable to parse input %q", scanner.Text())
+		}
+
+		if inputs[0] == "mask" {
+			c.input = append(c.input, command{
+				isMask: true,
+				mask:   inputs[1],
+			})
+		} else {
+			var pointer, mem int
+			count, err := fmt.Sscanf(inputs[0], "mem[%d]", &pointer)
+			if count != 1 || err != nil {
+				return fmt.Errorf("Unable to parse memory location from %s", inputs[0])
+			}
+			mem, err = strconv.Atoi(inputs[1])
+
+			c.input = append(c.input, command{
+				isMask:  false,
+				mem:     mem,
+				pointer: pointer,
+			})
+		}
+	}
+
+	c.memory = make(map[int]uint64, len(c.input))
+	return nil
+}
+
+func newComputer(filename string) *computer {
+	c := &computer{}
+	c.mask = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
+	c.executed = false
+	if err := c.load(filename); err != nil {
+		fmt.Println(err.Error())
+		return nil
+	}
+
+	return c
+}
+
+func (c *computer) execute() {
+	c.executed = true
+
+	for _, input := range c.input {
+		if input.isMask {
+			c.mask = input.mask
+			c.ones = 0
+			c.zeros = 0
+
+			for i := 0; i < len(input.mask); i++ {
+				switch string(input.mask[len(input.mask)-1-i]) {
+				case "0":
+					c.zeros += 1 << i
+				case "1":
+					c.ones += 1 << i
+				}
+			}
+
+			continue
+		}
+
+		value := uint64(input.mem)
+		value |= c.ones
+		value &^= c.zeros
+		c.memory[input.pointer] = value
+	}
+}
+
+func (c *computer) executeV2() {
+	c.executed = true
+
+	for _, input := range c.input {
+		if input.isMask {
+			c.mask = input.mask
+			c.ones = 0
+			c.zeros = 0
+			for i := 0; i < len(input.mask); i++ {
+				switch string(input.mask[len(input.mask)-1-i]) {
+				case "0":
+					c.zeros += 1 << i
+				case "1":
+					c.ones += 1 << i
+				}
+			}
+
+			continue
+		}
+
+		value := uint64(input.mem)
+		location := uint64(input.pointer) | c.ones
+
+		for _, p := range c.memMask(location) {
+			c.memory[p] = value
+		}
+	}
+}
+
+func (c *computer) memMask(p uint64) []int {
+	locations := []int{0}
+
+	for i := 0; i < len(c.mask); i++ {
+		switch string(c.mask[len(c.mask)-1-i]) {
+		case "X":
+			for j, l := range locations {
+				locations = append(locations, int(l|(1<<i)))
+				locations[j] = int(l &^ (1 << i))
+			}
+		case "1":
+			for j := 0; j < len(locations); j++ {
+				locations[j] = int(locations[j] | (1 << i))
+			}
+		case "0":
+			for j := 0; j < len(locations); j++ {
+				locations[j] = locations[j] | int(p&(1<<i))
+			}
+		}
+
+	}
+	return locations
+}
+
+func (c *computer) sum(version int) int {
+	if !c.executed {
+		switch version {
+		case 1:
+			c.execute()
+		case 2:
+			c.executeV2()
+		}
+	}
+
+	sum := 0
+	for _, v := range c.memory {
+		sum += int(v)
+	}
+
+	return sum
+}
+
+// PartOne Execute the initialization program
+func PartOne() string {
+	c := newComputer("fourteen/input.txt")
+	if c == nil {
+		return "Unable to load program"
+	}
+
+	return fmt.Sprintf("The memory value after execution is %d", c.sum(1))
+}
+
+// PartTwo Execute the initialization program with version 2
+func PartTwo() string {
+	c := newComputer("fourteen/input.txt")
+	if c == nil {
+		return "Unable to load program"
+	}
+
+	return fmt.Sprintf("The memory value after execution is %d", c.sum(2))
+}