2021 Day 11 Complete!

2021/day11/main.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"fmt"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(h.StringSliceToCoordByteMap(inp))
+	part2(h.StringSliceToCoordByteMap(inp))
+}
+
+func part1(m h.CoordByteMap) {
+	var count int
+	for i := 0; i < 100; i++ {
+		var wrk int
+		m, wrk = step(m)
+		count += wrk
+	}
+	fmt.Println("# Part 1")
+	fmt.Println("Total Flashes", count)
+}
+
+func part2(m h.CoordByteMap) {
+	var count int
+	var steps int
+	for count != len(m.Field) {
+		if steps%1000 == 0 {
+			fmt.Print("O")
+		} else if steps%100 == 0 {
+			fmt.Print("o")
+		} else if steps%10 == 0 {
+			fmt.Print(".")
+		}
+		m, count = step(m)
+		steps++
+	}
+	fmt.Println()
+	fmt.Println("# Part 2")
+	fmt.Println("Synchronized after", steps, "steps")
+}
+
+func step(m h.CoordByteMap) (h.CoordByteMap, int) {
+	var flashes []h.Coordinate
+	for y := 0; y < m.Height; y++ {
+		for x := 0; x < m.Width; x++ {
+			c := h.Coordinate{X: x, Y: y}
+			v := m.Get(c)
+			switch v {
+			case 0:
+				continue
+			case '9':
+				m.Put(c, '.')
+				flashes = append(flashes, c)
+			default:
+				m.Put(c, v+1)
+			}
+		}
+	}
+	for len(flashes) > 0 {
+		var next []h.Coordinate
+		for i := range flashes {
+			var wrk []h.Coordinate
+			m, wrk = flash(flashes[i], m)
+			next = append(next, wrk...)
+		}
+		flashes = next
+	}
+	var flashCount int
+	for y := 0; y < m.Height; y++ {
+		for x := 0; x < m.Width; x++ {
+			c := h.Coordinate{X: x, Y: y}
+			if m.Get(c) == 'o' {
+				m.Put(c, '0')
+				flashCount++
+			}
+		}
+	}
+	return m, flashCount
+}
+
+func flash(c h.Coordinate, m h.CoordByteMap) (h.CoordByteMap, []h.Coordinate) {
+	var flashes []h.Coordinate
+	m.Put(c, 'o')
+	for _, n := range []h.Coordinate{c.North(), c.NE(), c.East(), c.SE(), c.South(), c.SW(), c.West(), c.NW()} {
+		v := m.Get(n)
+		switch v {
+		case 0, '.', 'o':
+			continue
+		case '9':
+			m.Put(n, '.')
+			flashes = append(flashes, n)
+		default:
+			m.Put(n, v+1)
+		}
+		if v == 0 {
+			continue
+		}
+	}
+	return m, flashes
+}