129 lines
2.5 KiB
Go
129 lines
2.5 KiB
Go
package main
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import (
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"fmt"
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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.StdinToStringSlice()
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part1(inp)
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fmt.Println()
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part2(inp)
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}
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func part1(input []string) {
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m := h.StringSliceToCoordByteMap(input)
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fmt.Println("# Part 1")
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tiltNorth(&m)
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fmt.Println(calcLoad(&m))
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}
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func part2(input []string) {
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target := 1_000_000_000
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mapCache := make(map[string]int)
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m := h.StringSliceToCoordByteMap(input)
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var i = 0
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var ignoreCache bool
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for ; i <= target; i++ {
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tiltNorth(&m)
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tiltWest(&m)
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tiltSouth(&m)
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tiltEast(&m)
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if !ignoreCache {
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if v, ok := mapCache[m.String()]; ok && i > 200 {
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target = i + (target-v)%(i-v) - 1
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ignoreCache = true
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}
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mapCache[m.String()] = i
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}
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}
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fmt.Println("# Part 2")
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fmt.Println(calcLoad(&m))
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}
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func c(x, y int) h.Coordinate { return h.Coordinate{X: x, Y: y} }
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// m.FindAll returns a slice sorted Left->Right, Top->Bottom
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func tiltNorth(m *h.CoordByteMap) {
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rocks := m.FindAll('O')
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for i := range rocks {
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if rocks[i].Y == m.TLY {
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continue
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}
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mv := h.Coordinate{X: rocks[i].X, Y: rocks[i].Y}
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for m.Get(mv.North()) == '.' {
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mv.MoveNorth()
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}
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if !mv.Equals(rocks[i]) {
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m.Put(rocks[i], '.')
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m.Put(mv, 'O')
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}
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}
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}
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func tiltEast(m *h.CoordByteMap) {
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rocks := m.FindAll('O')
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for i, j := 0, len(rocks)-1; i < j; i, j = i+1, j-1 {
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rocks[i], rocks[j] = rocks[j], rocks[i]
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}
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for i := range rocks {
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if rocks[i].X == m.BRX {
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continue
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}
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mv := h.Coordinate{X: rocks[i].X, Y: rocks[i].Y}
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for m.Get(mv.East()) == '.' {
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mv.MoveEast()
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}
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if !mv.Equals(rocks[i]) {
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m.Put(rocks[i], '.')
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m.Put(mv, 'O')
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}
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}
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}
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func tiltSouth(m *h.CoordByteMap) {
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rocks := m.FindAll('O')
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for i, j := 0, len(rocks)-1; i < j; i, j = i+1, j-1 {
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rocks[i], rocks[j] = rocks[j], rocks[i]
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}
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for i := range rocks {
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if rocks[i].Y == m.BRY {
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continue
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}
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mv := h.Coordinate{X: rocks[i].X, Y: rocks[i].Y}
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for m.Get(mv.South()) == '.' {
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mv.MoveSouth()
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}
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if !mv.Equals(rocks[i]) {
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m.Put(rocks[i], '.')
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m.Put(mv, 'O')
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}
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}
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}
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func tiltWest(m *h.CoordByteMap) {
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rocks := m.FindAll('O')
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for i := range rocks {
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if rocks[i].X == m.TLX {
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continue
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}
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mv := h.Coordinate{X: rocks[i].X, Y: rocks[i].Y}
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for m.Get(mv.West()) == '.' {
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mv.MoveWest()
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}
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if !mv.Equals(rocks[i]) {
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m.Put(rocks[i], '.')
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m.Put(mv, 'O')
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}
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}
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}
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func calcLoad(m *h.CoordByteMap) int {
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var res int
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bot := m.BRY
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rocks := m.FindAll('O')
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for i := range rocks {
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res += (bot - rocks[i].Y) + 1
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}
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return res
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}
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