maze-solver-go/solver/a-star.go

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2023-08-15 18:43:18 +02:00
package solver
import (
"maze-solver/maze"
"maze-solver/utils"
"sort"
)
type AStarSolver struct {
dist_from_start map[*maze.Node]int
dist_from_end map[*maze.Node]int
parent map[*maze.Node]*maze.Node
stack sorted_stack
}
func (s *AStarSolver) Solve(m *maze.Maze) *maze.SolvedMaze {
defer utils.Timer("A* algorithm", 2)()
s.dist_from_start = make(map[*maze.Node]int, len(m.Nodes))
s.dist_from_end = make(map[*maze.Node]int, len(m.Nodes))
s.parent = make(map[*maze.Node]*maze.Node, len(m.Nodes))
current, end := m.Nodes[0], m.Nodes[len(m.Nodes)-1]
for _, node := range m.Nodes {
s.dist_from_start[node] = 0
s.dist_from_end[node] = int(node.Coords.Distance(end.Coords))
}
for current != end {
current.Visited = true
for _, child := range []*maze.Node{current.Left, current.Right, current.Up, current.Down} {
if child != nil {
dist := s.dist_from_start[current] + int(current.Coords.Distance(child.Coords))
if !child.Visited {
s.parent[child] = current
s.dist_from_start[child] = dist
s.stack.insert(child, &s.dist_from_end)
} else if s.dist_from_start[child] > dist {
s.parent[child] = current
s.dist_from_start[child] = dist
sort.Slice(s.stack, func(i, j int) bool {
return s.dist_from_end[s.stack[i]] < s.dist_from_end[s.stack[j]]
})
}
}
}
current = s.stack.pop()
}
solution := make([]*maze.Node, 0, len(m.Nodes))
for current != m.Nodes[0] {
solution = append(solution, current)
current = s.parent[current]
}
solution = append(solution, m.Nodes[0])
for i, j := 0, len(solution)-1; i < j; i, j = i+1, j-1 {
solution[i], solution[j] = solution[j], solution[i]
}
return &maze.SolvedMaze{
Maze: m,
Solution: solution,
}
}