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