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permutations iterator

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This commit is contained in:
Joseph Montanaro 2021-03-18 23:23:19 -07:00
parent c552834741
commit 86ef069848
1 changed files with 20 additions and 5 deletions
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23
main.nim
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@ -1,4 +1,4 @@
import options, sequtils, sugar import algorithm, options, sequtils, sugar
type type
@ -18,6 +18,7 @@ type
Board = object Board = object
squares: array[1..16, Square] squares: array[1..16, Square]
camels: array[Color, range[1..16]] camels: array[Color, range[1..16]]
leader: Color
proc `[]`(b: var Board, idx: range[1..16]): var Square = proc `[]`(b: var Board, idx: range[1..16]): var Square =
@ -58,18 +59,32 @@ proc advance(b: var Board, die: Die) =
for i, c in b[startPos].camels: for i, c in b[startPos].camels:
if c == color: if c == color:
let subStack = b[startPos].camels[i .. ^1] let subStack = b[startPos].camels[i .. ^1]
b[endPos].camels.add(subStack)
if prepend: if prepend:
# figure out how to prepend a sequence to another sequence b[endPos].camels.insert(subStack)
else: else:
b[endPos].camels.add(subStack)
b[startPos].camels[i .. ^1] = @[] b[startPos].camels[i .. ^1] = @[]
for moved in subStack: for moved in subStack:
b.camels[moved] = endPos b.camels[moved] = endPos
b.leader = b[b.camels.max][^1] # top camel in the last currently-occupied space
break # breaking the outer loop here, not the inner break # breaking the outer loop here, not the inner
iterator allPermutations[T](x: seq[T]): seq[T] =
# returns all permutations of a given array. Order is wonky but we don't care.
var workingCopy = x
yield workingCopy
while workingCopy.nextPermutation: # this mutates workingCopy
yield workingCopy
workingCopy = x
while workingCopy.prevPermutation:
yield workingCopy
var b: Board var b: Board
# b.display(1, 5) b.display(1, 5)
b.preRoll b.preRoll
let c = b.dup(advance((cRed, range[1..3]3))) let c = b.dup(advance((cRed, range[1..3]3)))
b.display(1, 5) b.display(1, 5)