2023 Day 22 Complete

Day 21, part 1 complete

2023/day21/main.go

@@ -0,0 +1,194 @@
+package main
+
+import (
+	"fmt"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(input []string) {
+	m := h.StringSliceToCoordByteMap(input)
+	start, _ := m.FindFirst('S')
+	m.Put(start, '.')
+	result := []h.Coordinate{start}
+	for i := 0; i < 64; i++ {
+		result = findNext(&m, result)
+	}
+	fmt.Println("# Part 1")
+	fmt.Println(len(result))
+}
+
+// 253370351984188 is too low
+func part2(input []string) {
+	m := h.StringSliceToCoordByteMap(input)
+	start, _ := m.FindFirst('S')
+	m.Put(start, '.')
+	steps := 26501365
+	p := make([]int, 3)
+	size := len(input)
+	half := size / 2
+	fmt.Println("Getting Plots: p[0]")
+	p[0], _ = getPlots(&m, half, 5)
+	fmt.Println("Getting Plots: p[1]")
+	m = h.StringSliceToCoordByteMap(input)
+	p[1], _ = getPlots(&m, half+size, 5)
+	fmt.Println("Getting Plots: p[2]")
+	m = h.StringSliceToCoordByteMap(input)
+	p[2], _ = getPlots(&m, half+2*size, 5)
+	a := (p[2] + p[0] - 2*p[1]) / 2
+	b := p[1] - p[0] - a
+	c := p[0]
+	n := steps / size
+	result := a*n*n + b*n + c
+
+	fmt.Println("# Part 2")
+	fmt.Println(result)
+}
+
+var visited map[string]bool
+
+func getPlots(m *h.CoordByteMap, steps int, factor int) (int, error) {
+	sx, sy := m.ColCount(), m.RowCount()
+	l := sy
+	expandMap(m, factor)
+	sx = l * (factor / 2)
+	sy = l * (factor / 2)
+	visited = make(map[string]bool)
+	return len(nextStep(sx, sy, 0, steps, m)), nil
+}
+
+func isPlot(m *h.CoordByteMap, x, y int) bool {
+	return m.Get(h.Coordinate{X: x, Y: y}) == '.'
+}
+func nextStep(x, y, step, max int, m *h.CoordByteMap) []h.Coordinate {
+	var acc []h.Coordinate
+	var key = fmt.Sprintf("%d;%d;%d", x, y, step)
+	if _, ok := visited[key]; ok {
+		return []h.Coordinate{}
+	} else {
+		visited[key] = true
+	}
+	if step == max {
+		return []h.Coordinate{{X: x, Y: y}}
+	}
+	if x > 0 && isPlot(m, x-1, y) {
+		acc = append(acc, nextStep(x-1, y, step+1, max, m)...)
+	}
+	if x < m.ColCount() && isPlot(m, x+1, y) {
+		acc = append(acc, nextStep(x, y-1, step+1, max, m)...)
+	}
+	if y > 0 && isPlot(m, x, y-1) {
+		acc = append(acc, nextStep(x, y-1, step+1, max, m)...)
+	}
+	if y < m.RowCount() && isPlot(m, x, y+1) {
+		acc = append(acc, nextStep(x, y+1, step+1, max, m)...)
+	}
+	return acc
+}
+
+func expandMap(m *h.CoordByteMap, factor int) {
+	stx, edx := m.TLX, m.BRX
+	for f := 1; f < factor; f++ {
+		for x := stx; x <= edx; x++ {
+			col := m.GetCol(x)
+			m.AddCol(col)
+		}
+		sty, edy := m.TLY, m.BRY
+		for y := sty; y <= edy; y++ {
+			row := m.GetRow(y)
+			m.AddRow(row)
+		}
+	}
+}
+
+func part2BruteForce(input []string) {
+	// Brute force just isn't going to cut it...
+	m := h.StringSliceToCoordByteMap(input)
+	m.StringEmptyIsSpace = true
+	m.StringEmptyByte = '.'
+	seen := make(map[h.Coordinate]bool)
+	start, _ := m.FindFirst('S')
+	m.Put(start, '.')
+	result := []h.Coordinate{start}
+	steps := 26501365
+	for i := 0; i < steps; i++ {
+		fmt.Println(h.CLEAR_SCREEN)
+		fmt.Printf("%d/%d (%f)\n", i, steps, float64(i)/float64(steps))
+		seen, result = findNextInfiniteRepeat(&m, seen, result)
+		if i == 100 {
+			break
+		}
+	}
+	fmt.Println("# Part 2")
+	fmt.Println(len(result))
+	for i := range result {
+		m.Put(result[i], 'O')
+	}
+	fmt.Println(m)
+	// It's making a diamond shape...
+}
+
+func findNext(m *h.CoordByteMap, curr []h.Coordinate) []h.Coordinate {
+	var result []h.Coordinate
+	for _, c := range curr {
+		for _, tst := range []h.Coordinate{
+			c.North(), c.East(), c.South(), c.West(),
+		} {
+			if m.ContainsCoord(tst) && m.Get(tst) == '.' {
+				var contains bool
+				for i := range result {
+					if result[i].Equals(tst) {
+						contains = true
+						break
+					}
+				}
+				if !contains {
+					result = append(result, tst)
+				}
+			}
+		}
+	}
+	return result
+}
+
+func findNextInfiniteRepeat(m *h.CoordByteMap, seen map[h.Coordinate]bool, curr []h.Coordinate) (map[h.Coordinate]bool, []h.Coordinate) {
+	var result []h.Coordinate
+	for _, c := range curr {
+		for _, tst := range []h.Coordinate{
+			c.North(), c.East(), c.South(), c.West(),
+		} {
+			if seen[tst] {
+				continue
+			}
+			wrkX, wrkY := tst.X, tst.Y
+			for wrkX < m.TLX {
+				wrkX += m.BRX
+			}
+			for wrkY < m.TLY {
+				wrkY += m.BRY
+			}
+			wrk := h.Coordinate{X: (wrkX % m.BRX), Y: (wrkY % m.BRY)}
+			if m.Get(wrk) == '.' {
+				var contains bool
+				for i := range result {
+					if result[i].Equals(tst) {
+						contains = true
+						break
+					}
+				}
+				if !contains {
+					result = append(result, tst)
+					seen[tst] = true
+				}
+			}
+		}
+	}
+	return seen, result
+}