2023 Day 13 Complete!

2023-12-13 09:21:48 -06:00
parent ea9a19d034
commit ed635d9088
6 changed files with 1794 additions and 1 deletions
--- a/2023/day13/main.go
+++ b/2023/day13/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) {
+	var maps []*h.CoordByteMap
+	var wrkInput []string
+	bld := func() {
+		m := h.StringSliceToCoordByteMap(wrkInput)
+		maps = append(maps, &m)
+		wrkInput = []string{}
+	}
+	for i := range input {
+		if len(input[i]) == 0 {
+			bld()
+		} else {
+			wrkInput = append(wrkInput, input[i])
+		}
+	}
+	if len(wrkInput) > 0 {
+		bld()
+	}
+
+	var result int
+	for _, m := range maps {
+		result += findMirror(m, -1)
+	}
+	fmt.Println("# Part 1")
+	fmt.Println(result)
+}
+
+func part2(input []string) {
+	var maps []*h.CoordByteMap
+	var wrkInput []string
+	bld := func() {
+		m := h.StringSliceToCoordByteMap(wrkInput)
+		maps = append(maps, &m)
+		wrkInput = []string{}
+	}
+	for i := range input {
+		if len(input[i]) == 0 {
+			bld()
+		} else {
+			wrkInput = append(wrkInput, input[i])
+		}
+	}
+	if len(wrkInput) > 0 {
+		bld()
+	}
+
+	var result int
+	for _, m := range maps {
+		result += checkForSmudge(m)
+	}
+	fmt.Println("# Part 2")
+	fmt.Println(result)
+}
+
+func checkForSmudge(m *h.CoordByteMap) int {
+	origMirror := findMirror(m, -1)
+	for y := m.TLY; y <= m.BRY; y++ {
+		for x := m.TLX; x <= m.BRX; x++ {
+			orig := m.Get(c(x, y))
+			switch orig {
+			case '#':
+				m.Put(c(x, y), '.')
+			case '.':
+				m.Put(c(x, y), '#')
+			}
+			res := findMirror(m, origMirror)
+			if res > 0 && res != origMirror {
+				return res
+			}
+			m.Put(c(x, y), orig)
+		}
+	}
+	return 0
+}
+
+// findMirror finds a mirror in the map
+// returning the value of that mirror (vertical (x+1), horizontal (y+1)* 100)
+func findMirror(m *h.CoordByteMap, exclude int) int {
+	var found bool
+	for x := m.TLX; x <= m.BRX; x++ {
+		val := (x + 1)
+		if found = checkForVerticalMirror(m, x, x+1); found && val != exclude {
+			return x + 1
+		}
+	}
+	for y := m.TLY; y <= m.BRY; y++ {
+		val := (y + 1) * 100
+		if found = checkForHorizontalMirror(m, y, y+1); found && val != exclude {
+			return (y + 1) * 100
+		}
+	}
+	return 0
+}
+
+func c(x, y int) h.Coordinate {
+	return h.Coordinate{X: x, Y: y}
+}
+
+func checkForVerticalMirror(m *h.CoordByteMap, x1, x2 int) bool {
+	var wrkX1, wrkX2 int
+	for y := m.TLY; y <= m.BRY; y++ {
+		wrkX1, wrkX2 = x1, x2
+		var match, cont bool
+		for wrkX1 >= m.TLX || wrkX2 <= m.BRX {
+			if match, cont = hPointsMatch(m, y, wrkX1, wrkX2); match {
+				if cont {
+					break
+				}
+				wrkX1--
+				wrkX2++
+			} else {
+				return false
+			}
+		}
+		if cont {
+			continue
+		}
+		if wrkX1 < m.TLX || wrkX2 > m.BRX {
+			return false
+		}
+	}
+	// Mirrors _shouldn't_ be at the very edge (or else what are we even doing here)
+	if wrkX1 == m.BRX || wrkX2 == m.TLX {
+		return false
+	}
+	return true
+}
+
+func hPointsMatch(m *h.CoordByteMap, y, x1, x2 int) (bool, bool) {
+	c1, c2 := c(x1, y), c(x2, y)
+	// If either is off the map, it could be
+	if m.Opt(c1, byte(0)) == 0 || m.Opt(c2, byte(0)) == 0 {
+		return true, true
+	}
+	// Check if (x1, y) == (x2, y)
+	v1, v2 := m.Get(c1), m.Get(c2)
+	return v1 == v2, false
+}
+
+func checkForHorizontalMirror(m *h.CoordByteMap, y1, y2 int) bool {
+	var wrkY1, wrkY2 int
+	for x := m.TLX; x <= m.BRX; x++ {
+		wrkY1, wrkY2 = y1, y2
+		var match, cont bool
+		for wrkY1 >= m.TLY || wrkY2 <= m.BRY {
+			if match, cont = vPointsMatch(m, x, wrkY1, wrkY2); match {
+				if cont {
+					break
+				}
+				wrkY1--
+				wrkY2++
+			} else {
+				return false
+			}
+		}
+		if cont {
+			continue
+		}
+		if wrkY1 > m.TLY && wrkY2 < m.BRY {
+			return false
+		}
+	}
+	// Mirrors _shouldn't_ be at the very edge (or else what are we even doing here)
+	if wrkY1 == m.BRY || wrkY2 == m.TLY {
+		return false
+	}
+	return true
+}
+
+func vPointsMatch(m *h.CoordByteMap, x, y1, y2 int) (bool, bool) {
+	c1, c2 := c(x, y1), c(x, y2)
+	// If either is off the map, it could be
+	if m.Opt(c1, byte(0)) == 0 || m.Opt(c2, byte(0)) == 0 {
+		return true, true
+	}
+	// Check if (x, y1) == (x, y2)
+	v1, v2 := m.Get(c1), m.Get(c2)
+	return v1 == v2, false
+}