95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
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package soko
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func Solve(l Level) int {
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state := l.State()
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return solve(state)
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}
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func solve(state State) int {
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level := state.Level
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target := state.Target.Pos
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costs := &stateCostQueue{}
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costs.Put(&stateCost{&state, 0, nil})
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costsByPlayerIdx := make([][]*stateCost, level.Size())
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findCost := func(s *State) *stateCost {
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costs := costsByPlayerIdx[s.Player.Pos]
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for i := 0; i < len(costs); i++ {
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if !costs[i].state.Equal(s) {
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continue
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}
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return costs[i]
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}
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return nil
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}
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addCost := func(next *State, nextCost int) {
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cost := findCost(next)
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if cost == nil {
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newCost := &stateCost{next, nextCost, nil}
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costs.Put(newCost)
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player := next.Player.Pos
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costsByPlayerIdx[player] = append(costsByPlayerIdx[player], newCost)
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} else if nextCost < cost.cost {
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cost.cost = nextCost
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costs.Update(cost)
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}
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}
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moves := level.Moves()
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type direction struct {
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dir Direction
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inverse Direction
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}
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dirs := make([]direction, 4)
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for _, dir := range Directions {
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dirs[dir] = direction{dir, dir.Invert()}
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}
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for {
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curr := costs.Get()
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currPlayerPos := curr.state.Player.Pos
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if currPlayerPos == target {
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return curr.cost
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}
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if curr.distances == nil {
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curr.distances = NewPathFinderMoves(curr.state, moves).FindDistances()
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}
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distances := curr.distances
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for _, e := range curr.state.Entities {
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idx := e.Pos
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if e.Typ != EntityTypeBrick || curr.state.SunkenBricks[idx] == e.ID {
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continue
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}
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for i := 0; i < 4; i++ {
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player := moves[e.Pos].All[dirs[i].inverse]
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if player == -1 {
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continue
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}
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walk := distances[player]
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if walk == -1 {
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continue
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}
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if !curr.state.IsOpenForBrick(curr.state.IdxToPos[moves[e.Pos].All[i]]) {
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continue
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}
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curr.state.Player.Pos = player
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next, ok := curr.state.MovePlayer(dirs[i].dir)
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if !ok {
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panic("should be a valid move")
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}
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nextCost := curr.cost + walk + 1
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addCost(&next, nextCost)
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}
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}
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curr.state.Player.Pos = currPlayerPos
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if walk := distances[target]; walk != -1 {
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next := curr.state.Clone()
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next.Player.Pos = target
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nextCost := curr.cost + walk
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addCost(&next, nextCost)
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}
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if costs.Empty() {
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return -1
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}
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}
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}
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