day 11

11/main.go

@@ -0,0 +1,147 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"time"
+)
+
+func mustAtoi(line byte) int {
+	i, _ := strconv.Atoi(string(line))
+	return i
+}
+
+func main() {
+	start := time.Now()
+	partOne()
+	duration := time.Since(start)
+	partTwo()
+	duration2 := time.Since(start)
+	fmt.Printf("p1: %s, p2: %s\n", duration, duration2-duration)
+}
+
+func makeScanner(test bool) *bufio.Scanner {
+	var f *os.File
+	if test {
+		f, _ = os.Open("inputs/testinput")
+	} else {
+		f, _ = os.Open("inputs/input")
+	}
+	reader := bufio.NewReader(f)
+	return bufio.NewScanner(reader)
+}
+
+type octopus struct {
+	energy  int
+	flashed bool
+}
+
+type octopi []octopus // index is col + (row*10)
+
+func (o *octopi) incrementEnergyLevels() {
+	for i := range *o {
+		(*o)[i].energy++
+	}
+}
+
+func (o *octopi) flash() bool {
+	flash := false
+	toIncrement := make([]int, 100)
+	for i := range *o {
+		if (*o)[i].energy > 9 && !(*o)[i].flashed {
+			(*o)[i].flashed = true
+			flash = true
+			if i > 9 {
+				toIncrement[i-10]++ // above
+			}
+			if i < 90 {
+				toIncrement[i+10]++ // below
+			}
+			if i%10 != 9 {
+				toIncrement[i+1]++ // right
+			}
+			if i%10 != 0 {
+				toIncrement[i-1]++ // left
+			}
+			if i%10 != 0 && i > 9 {
+				toIncrement[i-11]++ // above-left
+			}
+			if i%10 != 9 && i > 9 {
+				toIncrement[i-9]++ // above-right
+			}
+			if i%10 != 0 && i < 90 {
+				toIncrement[i+9]++ // below-left
+			}
+			if i%10 != 9 && i < 90 {
+				toIncrement[i+11]++ // below-right
+			}
+		}
+	}
+	for i := range toIncrement {
+		(*o)[i].energy += toIncrement[i]
+	}
+	return flash
+}
+
+func (o *octopi) reset() int {
+	count := 0
+	for i := range *o {
+		if (*o)[i].energy > 9 {
+			count++
+			(*o)[i].energy = 0
+			(*o)[i].flashed = false
+		}
+	}
+	return count
+}
+
+func partOne() {
+	scanner := makeScanner(false)
+
+	cave := octopi{}
+	for scanner.Scan() {
+		line := scanner.Text()
+		for i := range line {
+			cave = append(cave, octopus{energy: mustAtoi(line[i])})
+		}
+	}
+	total := 0
+	for step := 0; step < 100; step++ {
+		cave.incrementEnergyLevels()
+		for {
+			if !cave.flash() {
+				break
+			}
+		}
+		total += cave.reset()
+	}
+	fmt.Println(total)
+}
+
+func partTwo() {
+	scanner := makeScanner(false)
+
+	cave := octopi{}
+	for scanner.Scan() {
+		line := scanner.Text()
+		for i := range line {
+			cave = append(cave, octopus{energy: mustAtoi(line[i])})
+		}
+	}
+	step := 0
+	for {
+		step++
+		cave.incrementEnergyLevels()
+		for {
+			if !cave.flash() {
+				break
+			}
+		}
+		if cave.reset() == 100 {
+			break
+		}
+	}
+	fmt.Println(step)
+}