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Mind boggling card trick: Difference between revisions
→{{header|Nim}}
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True // the result is TRUE
</pre>
=={{header|Nim}}==
{{trans|Kotlin}}
<lang Nim>import random, sequtils, strformat, strutils
type Color {.pure.} = enum Red = "R", Black = "B"
proc `$`(s: seq[Color]): string = s.join(" ")
# Create pack, half red, half black and shuffle it.
var pack = newSeq[Color](52)
for i in 0..51: pack[i] = Color(i < 26)
pack.shuffle()
# Deal from pack into 3 stacks.
var red, black, others: seq[Color]
for i in countup(0, 51, 2):
case pack[i]
of Red: red.add pack[i + 1]
of Black: black.add pack[i + 1]
others.add pack[i]
echo "After dealing the cards the state of the stacks is:"
echo &" Red: {red.len:>2} cards -> {red}"
echo &" Black: {black.len:>2} cards -> {black}"
echo &" Discard: {others.len:>2} cards -> {others}"
# Swap the same, random, number of cards between the red and black stacks.
let m = min(red.len, black.len)
let n = rand(1..m)
var rp = toSeq(0..red.high)
rp.shuffle()
rp.setLen(n)
var bp = toSeq(0..black.high)
bp.shuffle()
bp.setLen(n)
echo &"\n{n} card(s) are to be swapped.\n"
echo "The respective zero-based indices of the cards(s) to be swapped are:"
echo " Red : ", rp.join(" ")
echo " Black : ", bp.join(" ")
for i in 0..<n:
swap red[rp[i]], black[bp[i]]
echo "\nAfter swapping, the state of the red and black stacks is:"
echo " Red : ", red
echo " Black : ", black
# Check that the number of black cards in the black stack equals
# the number of red cards in the red stack.
let rcount = red.count(Red)
let bcount = black.count(Black)
echo ""
echo "The number of red cards in the red stack is ", rcount
echo "The number of black cards in the black stack is ", bcount
if rcount == bcount:
echo "So the asssertion is correct."
else:
echo "So the asssertion is incorrect."</lang>
{{out}}
<pre>After dealing the cards the state of the stacks is:
Red: 14 cards -> B B B B R R B B R B R R R B
Black: 12 cards -> R R R B R B B R B B R B
Discard: 26 cards -> B B R R R R B B B R R R R R B B B R R B R B R B B R
6 card(s) are to be swapped.
The respective zero-based indices of the cards(s) to be swapped are:
Red : 6 9 10 5 13 3
Black : 7 4 5 8 2 11
After swapping, the state of the red and black stacks is:
Red : B B B B R B R B R R B R R R
Black : R R B B B R B B R B R B
The number of red cards in the red stack is 7
The number of black cards in the black stack is 7
So the asssertion is correct.</pre>
=={{header|Perl}}==
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