feat: implememented dijkstra algorithm

This commit is contained in:
Karma Riuk 2023-08-15 17:22:10 +02:00
parent 49d98d84d2
commit 6dbb3437e7
2 changed files with 91 additions and 2 deletions

85
solver/dijkstra.go Normal file
View File

@ -0,0 +1,85 @@
package solver
import (
"maze-solver/maze"
"maze-solver/utils"
"slices"
"sort"
)
type DijkstraSolver struct {
dist_from_start map[*maze.Node]int
parent map[*maze.Node]*maze.Node
stack sorted_stack
}
type sorted_stack []*maze.Node
func (s *DijkstraSolver) Solve(m *maze.Maze) *maze.SolvedMaze {
defer utils.Timer("Dijkstra algorithm", 2)()
s.dist_from_start = make(map[*maze.Node]int, len(m.Nodes))
s.parent = make(map[*maze.Node]*maze.Node, len(m.Nodes))
for _, node := range m.Nodes {
s.dist_from_start[node] = 0
}
current, end := m.Nodes[0], m.Nodes[len(m.Nodes)-1]
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_start)
} 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_start[s.stack[i]] < s.dist_from_start[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,
}
}
func (s *sorted_stack) insert(node *maze.Node, dists *map[*maze.Node]int) {
var dummy *maze.Node
*s = append(*s, dummy) // extend the slice
i, _ := slices.BinarySearchFunc(*s, node, func(e, t *maze.Node) int {
return (*dists)[t] - (*dists)[e]
})
copy((*s)[i+1:], (*s)[i:]) // make room
(*s)[i] = node
}
func (s *sorted_stack) pop() *maze.Node {
last_i := len(*s) - 1
ret := (*s)[last_i]
*s = (*s)[:last_i]
return ret
}

View File

@ -14,13 +14,15 @@ type SolverFactory struct {
} }
const ( const (
_DFS = "dfs" _DFS = "dfs"
_BFS = "bfs" _BFS = "bfs"
_Dijkstra = "dijkstra"
) )
var TYPES = []string{ var TYPES = []string{
_DFS, _DFS,
_BFS, _BFS,
_Dijkstra,
} }
func (f *SolverFactory) Get() Solver { func (f *SolverFactory) Get() Solver {
@ -29,6 +31,8 @@ func (f *SolverFactory) Get() Solver {
return &DFSSolver{} return &DFSSolver{}
case _BFS: case _BFS:
return &BFSSolver{} return &BFSSolver{}
case _Dijkstra:
return &DijkstraSolver{}
} }
panic(fmt.Sprintf("Unrecognized solver type %q", *f.Type)) panic(fmt.Sprintf("Unrecognized solver type %q", *f.Type))
} }