2024 Day 6 Complete!

2024/day06/main.go

@@ -0,0 +1,148 @@
+package main
+
+import (
+	"fmt"
+	"time"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToCoordMap()
+	cp := inp.Copy()
+	m := part1(inp)
+	part2(*cp, m.FindAll('X'))
+}
+
+var debug = false
+
+func part1(m h.CoordByteMap) h.CoordByteMap {
+	init, err := m.FindFirst('^')
+	h.CheckErr(err)
+	for moveGuard(m) {
+		if debug {
+			fmt.Println(h.CLEAR_SCREEN)
+			fmt.Println(m)
+			guard := m.FindAll('^', '>', 'v', '<')[0]
+			fmt.Println(guard)
+			time.Sleep(time.Second / 10)
+		}
+	}
+	fmt.Println()
+	fmt.Println("# Part 1")
+	fmt.Printf("Guard moved into %d positions.\n", m.Count('X'))
+	fmt.Println()
+	m.Put(init, '^')
+	return m
+}
+
+func part2(clean h.CoordByteMap, p []h.Coordinate) {
+	// m should have all of the 'X' spots where the guard moved in part 1
+	init, err := clean.FindFirst('^')
+	h.CheckErr(err)
+	var obstacles []h.Coordinate
+	for i := range p {
+		fmt.Println(h.CLEAR_SCREEN)
+		fmt.Print("Progress: ")
+		h.PrintProgress(i, len(p))
+		fmt.Printf(" %d/%d\n", i, len(p))
+		m := *clean.Copy()
+		// Try putting an obstacle at p[i]
+		m.Put(p[i], 'O')
+		history := make(map[h.Coordinate][]string)
+		guard := m.FindAll('^', '>', 'v', '<')[0]
+		tst := m.Get(guard)
+		history[guard] = append(history[guard], string(tst))
+		var foundLoop bool
+		for moveGuard(m) && !foundLoop {
+			// fmt.Print(".")
+			if debug {
+				fmt.Println(h.CLEAR_SCREEN)
+				fmt.Println(m)
+				guard := m.FindAll('^', '>', 'v', '<')[0]
+				fmt.Printf("Guard: %s - Testing Obstacle: %s\n", guard, p[i])
+				fmt.Println(obstacles)
+				fmt.Println(history)
+				time.Sleep(time.Second / 10)
+			}
+			guard := m.FindAll('^', '>', 'v', '<')[0]
+			bt := m.Get(guard)
+			// Check if we already have this position/orientation in our history
+			for j := range history[guard] {
+				if history[guard][j] == string(bt) {
+					if !contains(obstacles, p[i]) {
+						obstacles = append(obstacles, p[i])
+						foundLoop = true
+						if debug {
+							fmt.Println("Found Loop:", string(history[guard][j]), "==", string(bt))
+						}
+						break
+					}
+				}
+			}
+			history[guard] = append(history[guard], string(bt))
+		}
+		m.Put(p[i], '.')
+		m.Put(init, '^')
+	}
+	fmt.Println()
+	fmt.Println("# Part 2")
+	fmt.Printf("Obstacle positions to create a loop: %d\n", len(obstacles))
+	// 583 is too low
+}
+
+func checkForLoop(m h.CoordByteMap) {
+}
+
+func contains(sl []h.Coordinate, c h.Coordinate) bool {
+	for i := range sl {
+		if sl[i].Equals(c) {
+			return true
+		}
+	}
+	return false
+}
+
+func turn(g byte) byte {
+	switch g {
+	case '^':
+		return '>'
+	case '>':
+		return 'v'
+	case 'v':
+		return '<'
+	default:
+		return '^'
+	}
+}
+
+func nextPos(guard h.Coordinate, m h.CoordByteMap) h.Coordinate {
+	switch m.Get(guard) {
+	case '>':
+		return guard.East()
+	case 'v':
+		return guard.South()
+	case '<':
+		return guard.West()
+	}
+	return guard.North()
+}
+
+func moveGuard(m h.CoordByteMap) bool {
+	guard := m.FindAll('^', '>', 'v', '<')[0]
+	currBt := m.Get(guard)
+	turn := turn(currBt)
+	next := nextPos(guard, m)
+	if !m.ContainsCoord(next) {
+		m.Put(guard, 'X')
+		return false
+	}
+	tst := m.Get(next)
+	if tst == '#' || tst == 'O' {
+		m.Put(guard, turn)
+		return moveGuard(m)
+	}
+	m.Put(guard, 'X')
+	m.Put(next, currBt)
+	return true
+}