Knight's tour: Difference between revisions

Content added Content deleted
(Undo revision 310918 by Dmcbane (talk))
(Undo revision 310917 by Dmcbane (talk))
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=={{header|Elm}}==
=={{header|Elm}}==
<lang elm>module Main exposing (main)
<lang elm>import List exposing (concatMap, foldl, head,member,filter,length,minimum,concat,map,map2,tail)

⚫
import Browser exposing (element)
import List exposing (concatMap, foldl, head,member,filter,length,minimum,concat,map,map2,tail)
import List.Extra exposing (minimumBy, andThen)
import List.Extra exposing (minimumBy, andThen)
import String exposing (join)
import String exposing (join)
import Html as H
import Html as H
import Html.Attributes as HA
import Html.Attributes as HA
import Time exposing (Posix, every)
import Html.App exposing (program)
⚫
import Time exposing (Time,every, second)
import Svg exposing (rect, line, svg, g)
import Svg exposing (rect, line, svg, g)
import Svg.Events exposing (onClick)
import Svg.Events exposing (onClick)
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rowCount=20
rowCount=20
colCount=20
colCount=20
dt = 0.03


type alias Cell = (Int, Int)
type alias Cell = (Int, Int)


type alias Model =
type alias Model =
{ path : List Cell
{ path : List Cell
, board : List Cell
, board : List Cell
}
}


type Msg = NoOp | Tick Time | SetStart Cell
type Msg
= NoOp
| Tick Time.Posix
| SetStart Cell


init : () -> (Model,Cmd Msg)
init : (Model,Cmd Msg)
init _ =
init =
let board = (List.range 0 (rowCount-1))
let board = [0..rowCount-1] `andThen` \r ->
|> andThen
[0..colCount-1] `andThen` \c ->
(\r ->
[(r, c)]
(List.range 0 (colCount-1))
|> andThen
(\c ->
[(r, c)]
)
)
path = []
path = []
in (Model path board, Cmd.none)
in (Model path board, Cmd.none)


view : Model -> H.Html Msg
view : Model -> H.Html Msg
view model =
view model =
let
let
showChecker row col =
showChecker row col =
rect [ x <| String.fromInt col
rect [ x <| toString col
, y <| String.fromInt row
, y <| toString row
, width "1"
, width "1"
, height "1"
, height "1"
, fill <| if modBy 2 (row + col) == 0 then "blue" else "grey"
, fill <| if (row + col) % 2 == 0 then "blue" else "grey"
, onClick <| SetStart (row, col)
, onClick <| SetStart (row, col)
]
]
[]
[]


showMove (row0,col0) (row1,col1) =
showMove (row0,col0) (row1,col1) =
line [ x1 <| String.fromFloat ((toFloat col0) + 0.5)
line [ x1 <| toString ((toFloat col0) + 0.5)
, y1 <| String.fromFloat ((toFloat row0) + 0.5)
, y1 <| toString ((toFloat row0) + 0.5)
, x2 <| String.fromFloat ((toFloat col1) + 0.5)
, x2 <| toString ((toFloat col1) + 0.5)
, y2 <| String.fromFloat ((toFloat row1) + 0.5)
, y2 <| toString ((toFloat row1) + 0.5)
, style "stroke:yellow;stroke-width:0.05"
, style "stroke:yellow;stroke-width:0.05"
]
]
[]
[]


render mdl =
render model =
let checkers = mdl.board
let checkers = model.board `andThen` \(r,c) ->
|> andThen
[showChecker r c]
(\(r,c) ->
moves = case List.tail model.path of
[showChecker r c]
)
moves = case List.tail mdl.path of
Nothing -> []
Nothing -> []
Just tl -> List.map2 showMove mdl.path tl
Just tl -> List.map2 showMove model.path tl
in checkers ++ moves
in checkers ++ moves


unvisited = length model.board - length model.path
unvisited = length model.board - length model.path


center = [ HA.style "text-align" "center" ]
center = HA.style [ ( "text-align", "center") ]


in
in
H.div
H.div
[]
[]
[ H.h2 center [H.text "Knight's Tour"]
[ H.h2 [center] [H.text "Knight's Tour"]
, H.h2 center [H.text <| "Unvisited count : " ++ String.fromInt unvisited ]
, H.h2 [center] [H.text <| "Unvisited count : " ++ toString unvisited ]
, H.h2 center [H.text "(pick a square)"]
, H.h2 [center] [H.text "(pick a square)"]
, H.div
, H.div
center
[center]
[ svg
[ svg
[ version "1.1"
[ version "1.1"
, width (String.fromInt w)
, width (toString w)
, height (String.fromInt h)
, height (toString h)
, viewBox (join " "
, viewBox (join " "
[ String.fromInt 0
[ toString 0
, String.fromInt 0
, toString 0
, String.fromInt colCount
, toString colCount
, String.fromInt rowCount ])
, toString rowCount ])
]
]
[ g [] <| render model]
[ g [] <| render model]
]
]
]
]


nextMoves : Model -> Cell -> List Cell
nextMoves : Model -> Cell -> List Cell
nextMoves model (stRow,stCol) =
nextMoves model (stRow,stCol) =
let c = [ 1, 2, -1, -2]
let c = [ 1, 2, -1, -2]


km = c
km = c `andThen` \cRow ->
|> andThen
c `andThen` \cCol ->
(\cRow ->
if abs(cRow) == abs(cCol) then [] else [(cRow,cCol)]
c
|> andThen
(\cCol ->
if abs(cRow) == abs(cCol) then [] else [(cRow,cCol)]
)
)


jumps = List.map (\(kmRow,kmCol) -> (kmRow + stRow, kmCol + stCol)) km
jumps = List.map (\(kmRow,kmCol) -> (kmRow + stRow, kmCol + stCol)) km
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bestMove : Model -> Maybe Cell
bestMove : Model -> Maybe Cell
bestMove model =
bestMove model =
case List.head (model.path) of
case List.head (model.path) of
Nothing -> Nothing
Nothing -> Nothing
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update msg model =
update msg model =
let mo = case msg of
let mo = case msg of
SetStart start ->
SetStart start ->
{model | path = [start]}
{model | path = [start]}
Tick posix ->
Tick t ->
case model.path of
case model.path of
[] -> model
[] -> model
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subscriptions : Model -> Sub Msg
subscriptions : Model -> Sub Msg
subscriptions _ =
subscriptions _ =
Time.every 10 Tick
Time.every (dt * second) Tick


main =
main =
program
element
{ init = init
{ init = init
, view = view
, view = view
, update = update
, update = update
, subscriptions = subscriptions
, subscriptions = subscriptions
}
}</lang>



Link to live demo: http://dc25.github.io/knightsTourElm/
Link to live demo: http://dc25.github.io/knightsTourElm/
Retrieved from "https://rosettacode.org/wiki/Knight%27s_tour"