graphs #21
39
aoc_test.go
39
aoc_test.go
@ -195,3 +195,42 @@ func ExamplePriorityQueue() {
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// point 5 is 22 steps away.
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// point 6 is 19 steps away.
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}
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func TestStack(t *testing.T) {
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is := is.New(t)
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s := aoc.Stack(1,2,3,4)
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is.True(!s.IsEmpty())
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is.Equal(s.Pop(), 4)
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is.Equal(s.Pop(), 3)
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is.Equal(s.Pop(), 2)
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is.Equal(s.Pop(), 1)
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is.True(s.IsEmpty())
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s.Push(4,3,2,1)
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is.True(!s.IsEmpty())
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is.Equal(s.Pop(), 1)
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is.Equal(s.Pop(), 2)
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is.Equal(s.Pop(), 3)
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is.Equal(s.Pop(), 4)
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is.True(s.IsEmpty())
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}
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func TestGraph(t *testing.T) {
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is := is.New(t)
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var adjacencyList = map[int][]int{
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2: {3, 5, 1},
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1: {2, 4},
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3: {6, 2},
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4: {1, 5, 7},
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5: {2, 6, 8, 4},
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6: {3, 0, 9, 5},
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7: {4, 8},
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8: {5, 9, 7},
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9: {6, 0, 8},
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}
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g := aoc.Graph(aoc.WithAdjacencyList[int,int](adjacencyList))
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is.Equal(g.Neighbors(1), []int{2,4})
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is.Equal(map[int][]int(g.AdjacencyList()), adjacencyList)
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}
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96
grids.go
96
grids.go
@ -1,5 +1,10 @@
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package aoc
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import (
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"cmp"
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"sort"
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)
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type Vector struct {
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Offset Point[int]
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Scale int
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@ -76,3 +81,94 @@ func (m *Map[I,T]) Valid(p Point[I]) bool {
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rows, cols := m.Size()
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return p[0] >= 0 && p[0] < rows && p[1] >= 0 && p[1] < cols
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}
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type adjacencyList[V any, C comparable] map[C][]V
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type graph[V any, W cmp.Ordered, C comparable] map[C]*vertex[V, W]
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type graphOption[V any, W cmp.Ordered, C comparable] func(g *graph[V, W, C])
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type vertex[V any, W cmp.Ordered] struct {
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Value V
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Edges edges[V, W]
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}
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func (v *vertex[V, W]) Neighbors() []V {
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var nbs []V
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sort.Sort(v.Edges)
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for _, e := range v.Edges {
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nbs = append(nbs, e.Vertex.Value)
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}
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return nbs
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}
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type edge[V any, W cmp.Ordered] struct {
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Vertex *vertex[V, W]
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Weight W
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}
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type edges[V any, W cmp.Ordered] []edge[V, W]
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func (e edges[V, W]) Len() int { return len(e) }
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func (e edges[V, W]) Less(i, j int) bool { return e[i].Weight < e[j].Weight }
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func (e edges[V, W]) Swap(i, j int) { e[i], e[j] = e[j], e[i] }
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func Graph[V any, W cmp.Ordered, C comparable](opts ...graphOption[V, W, C]) *graph[V, W, C] {
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g := make(graph[V, W, C])
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for _, opt := range opts {
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opt(&g)
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}
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return &g
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}
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func (g *graph[V, W, C]) AddVertex(id C, value V) {
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(*g)[id] = &vertex[V,W]{Value: value}
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}
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func (g *graph[V, W, C]) AddEdge(from, to C, w W) {
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if g == nil {
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return
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}
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if _, ok := (*g)[from]; !ok {
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return
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}
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if _, ok := (*g)[to]; !ok {
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return
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}
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(*g)[from].Edges = append((*g)[from].Edges, edge[V,W]{(*g)[to], w})
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}
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func (g *graph[V, W, C]) Neighbors(v C) []V {
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if g == nil {
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return nil
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}
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return (*g)[v].Neighbors()
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}
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func (g *graph[V, W, C]) AdjacencyList() adjacencyList[V, C] {
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m := make(map[C][]V)
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for id, v := range *g {
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if len(v.Edges) == 0 {
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continue
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}
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m[id] = v.Neighbors()
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}
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return m
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}
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func WithAdjacencyList[W cmp.Ordered, C comparable](list adjacencyList[C, C]) graphOption[C, W, C] {
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var zeroW W
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return func(g *graph[C, W, C]) {
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for vertex, edges := range list {
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if _, ok := (*g)[vertex]; !ok {
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g.AddVertex(vertex, vertex)
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}
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// add edges to vertex
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for _, edge := range edges {
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// add edge as vertex, if not added
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if _, ok := (*g)[edge]; !ok {
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g.AddVertex(edge, edge)
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}
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g.AddEdge(vertex, edge, zeroW) // no weights in this adjacency list
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}
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}
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}
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}
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// func GraphFromMap()
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122
search.go
122
search.go
@ -1,6 +1,7 @@
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package aoc
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import (
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"maps"
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"sort"
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)
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@ -41,6 +42,30 @@ func (pq *priorityQueue[T]) Dequeue() (T, bool) {
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return elem, true
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}
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type stack[T any] []T
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func Stack[T any](a ...T) *stack[T] {
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var s stack[T] = a
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return &s
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}
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func (s *stack[T]) Push(a ...T) {
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if s == nil {
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return
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}
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*s = append(*s, a...)
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}
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func (s *stack[T]) IsEmpty() bool {
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return s == nil || len(*s) == 0
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}
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func (s *stack[T]) Pop() T {
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var a T
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if s.IsEmpty() {
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return a
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}
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a, *s = (*s)[len(*s)-1], (*s)[:len(*s)-1]
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return a
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}
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// ManhattanDistance the distance between two points measured along axes at right angles.
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func ManhattanDistance[T integer](a, b Point[T]) T {
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return ABS(a[1]-b[1]) + ABS(a[0]-b[0])
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@ -148,3 +173,100 @@ func FindPath[C integer, N comparable](g pather[C, N], start, end N) (C, []N) {
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}
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return zero, nil
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}
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// FindPath uses the A* path finding algorithem.
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// g is the graph source that implements the pather interface.
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//
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// C is an numeric type for calculating cost/potential
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// N is the node values. is comparable for storing in visited table for pruning.
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//
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// start, end are nodes that dileniate the start and end of the search path.
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// The returned values are the calculated cost and the path taken from start to end.
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func FindPaths[C integer, N comparable](g pather[C, N], start, end N) ([]C, [][]N) {
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var zero C
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// closed := make(map[N]bool)
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type node struct {
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cost C
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potential C
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parent *node
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position N
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closed map[N]bool
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}
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NewPath := func(n *node) []N {
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var path []N
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for n.parent != nil {
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path = append(path, n.position)
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n = n.parent
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}
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path = append(path, n.position)
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Reverse(path)
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return path
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}
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less := func(b, a node) bool {
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return b.cost+b.potential < a.cost+a.potential
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}
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pq := PriorityQueue(less)
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pq.Enqueue(node{position: start, closed: make(map[N]bool)})
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defer func() {
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Log("queue max depth = ", pq.maxDepth, "total enqueue = ", pq.totalEnqueue, "total dequeue = ", pq.totalDequeue)
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}()
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var seenFn = func(a N) N { return a }
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if s, ok := g.(interface{ Seen(N) N }); ok {
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seenFn = s.Seen
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}
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var targetFn = func(a N) bool { return true }
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if s, ok := g.(interface{ Target(N) bool }); ok {
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targetFn = s.Target
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}
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var paths [][]N
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var costs []C
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for !pq.IsEmpty() {
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current, _ := pq.Dequeue()
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cost, potential, n := current.cost, current.potential, current.position
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seen := seenFn(n)
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if current.closed[seen] {
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continue
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}
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current.closed[seen] = true
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if cost > 0 && potential == zero && cost > Max(0, costs...) && targetFn(current.position) {
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paths = append([][]N(nil), NewPath(¤t))
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costs = append([]C(nil), cost)
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Log("new record = ", cost)
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continue
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}
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for _, nb := range g.Neighbors(n) {
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seen := seenFn(nb)
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if current.closed[seen] {
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continue
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}
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cost := g.Cost(n, nb) + current.cost
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next := node{
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position: nb,
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parent: ¤t,
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cost: cost,
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potential: g.Potential(nb, end),
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closed: maps.Clone(current.closed),
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}
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// check if path is in open list
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if _, open := current.closed[seen]; !open {
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next.closed[seen] = false // add to open list
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pq.Enqueue(next)
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}
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}
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}
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return costs, paths
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}
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