Peaceful chess queen armies: Difference between revisions

Content added Content deleted
m (added a ;Task: section header, added whitespace before the TOC.)
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peacefulqueenapp()
peacefulqueenapp()
</lang>
</lang>

=={{header|Kotlin}}==
{{trans|D}}
<lang scala>import kotlin.math.abs

enum class Piece {
Empty,
Black,
White,
}

typealias Position = Pair<Int, Int>

fun place(m: Int, n: Int, pBlackQueens: MutableList<Position>, pWhiteQueens: MutableList<Position>): Boolean {
if (m == 0) {
return true
}
var placingBlack = true
for (i in 0 until n) {
inner@
for (j in 0 until n) {
val pos = Position(i, j)
for (queen in pBlackQueens) {
if (queen == pos || !placingBlack && isAttacking(queen, pos)) {
continue@inner
}
}
for (queen in pWhiteQueens) {
if (queen == pos || placingBlack && isAttacking(queen, pos)) {
continue@inner
}
}
placingBlack = if (placingBlack) {
pBlackQueens.add(pos)
false
} else {
pWhiteQueens.add(pos)
if (place(m - 1, n, pBlackQueens, pWhiteQueens)) {
return true
}
pBlackQueens.removeAt(pBlackQueens.lastIndex)
pWhiteQueens.removeAt(pWhiteQueens.lastIndex)
true
}
}
}
if (!placingBlack) {
pBlackQueens.removeAt(pBlackQueens.lastIndex)
}
return false
}

fun isAttacking(queen: Position, pos: Position): Boolean {
return queen.first == pos.first
|| queen.second == pos.second
|| abs(queen.first - pos.first) == abs(queen.second - pos.second)
}

fun printBoard(n: Int, blackQueens: List<Position>, whiteQueens: List<Position>) {
val board = MutableList(n * n) { Piece.Empty }

for (queen in blackQueens) {
board[queen.first * n + queen.second] = Piece.Black
}
for (queen in whiteQueens) {
board[queen.first * n + queen.second] = Piece.White
}
for ((i, b) in board.withIndex()) {
if (i != 0 && i % n == 0) {
println()
}
if (b == Piece.Black) {
print("B ")
} else if (b == Piece.White) {
print("W ")
} else {
val j = i / n
val k = i - j * n
if (j % 2 == k % 2) {
print("• ")
} else {
print("◦ ")
}
}
}
println('\n')
}

fun main() {
val nms = listOf(
Pair(2, 1), Pair(3, 1), Pair(3, 2), Pair(4, 1), Pair(4, 2), Pair(4, 3),
Pair(5, 1), Pair(5, 2), Pair(5, 3), Pair(5, 4), Pair(5, 5),
Pair(6, 1), Pair(6, 2), Pair(6, 3), Pair(6, 4), Pair(6, 5), Pair(6, 6),
Pair(7, 1), Pair(7, 2), Pair(7, 3), Pair(7, 4), Pair(7, 5), Pair(7, 6), Pair(7, 7)
)
for ((n, m) in nms) {
println("$m black and $m white queens on a $n x $n board:")
val blackQueens = mutableListOf<Position>()
val whiteQueens = mutableListOf<Position>()
if (place(m, n, blackQueens, whiteQueens)) {
printBoard(n, blackQueens, whiteQueens)
} else {
println("No solution exists.\n")
}
}
}</lang>
{{out}}
<pre>1 black and 1 white queens on a 2 x 2 board:
No solution exists.

1 black and 1 white queens on a 3 x 3 board:
B ◦ •
◦ • W
• ◦ •

2 black and 2 white queens on a 3 x 3 board:
No solution exists.

1 black and 1 white queens on a 4 x 4 board:
B ◦ • ◦
◦ • W •
• ◦ • ◦
◦ • ◦ •

2 black and 2 white queens on a 4 x 4 board:
B ◦ • ◦
◦ • W •
B ◦ • ◦
◦ • W •

3 black and 3 white queens on a 4 x 4 board:
No solution exists.

1 black and 1 white queens on a 5 x 5 board:
B ◦ • ◦ •
◦ • W • ◦
• ◦ • ◦ •
◦ • ◦ • ◦
• ◦ • ◦ •

2 black and 2 white queens on a 5 x 5 board:
B ◦ • ◦ B
◦ • W • ◦
• W • ◦ •
◦ • ◦ • ◦
• ◦ • ◦ •

3 black and 3 white queens on a 5 x 5 board:
B ◦ • ◦ B
◦ • W • ◦
• W • ◦ •
◦ • ◦ B ◦
• W • ◦ •

4 black and 4 white queens on a 5 x 5 board:
• B • B •
◦ • ◦ • B
W ◦ W ◦ •
◦ • ◦ • B
W ◦ W ◦ •

5 black and 5 white queens on a 5 x 5 board:
No solution exists.

1 black and 1 white queens on a 6 x 6 board:
B ◦ • ◦ • ◦
◦ • W • ◦ •
• ◦ • ◦ • ◦
◦ • ◦ • ◦ •
• ◦ • ◦ • ◦
◦ • ◦ • ◦ •

2 black and 2 white queens on a 6 x 6 board:
B ◦ • ◦ B ◦
◦ • W • ◦ •
• W • ◦ • ◦
◦ • ◦ • ◦ •
• ◦ • ◦ • ◦
◦ • ◦ • ◦ •

3 black and 3 white queens on a 6 x 6 board:
B ◦ • ◦ B B
◦ • W • ◦ •
• W • ◦ • ◦
◦ • ◦ • ◦ •
• ◦ W ◦ • ◦
◦ • ◦ • ◦ •

4 black and 4 white queens on a 6 x 6 board:
B ◦ • ◦ B B
◦ • W • ◦ •
• W • ◦ • ◦
◦ • ◦ • ◦ B
• ◦ W W • ◦
◦ • ◦ • ◦ •

5 black and 5 white queens on a 6 x 6 board:
• B • ◦ B ◦
◦ • ◦ B ◦ B
W ◦ • ◦ • ◦
W • W • ◦ •
• ◦ • ◦ • B
W • W • ◦ •

6 black and 6 white queens on a 6 x 6 board:
No solution exists.

1 black and 1 white queens on a 7 x 7 board:
B ◦ • ◦ • ◦ •
◦ • W • ◦ • ◦
• ◦ • ◦ • ◦ •
◦ • ◦ • ◦ • ◦
• ◦ • ◦ • ◦ •
◦ • ◦ • ◦ • ◦
• ◦ • ◦ • ◦ •

2 black and 2 white queens on a 7 x 7 board:
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
• ◦ • ◦ • ◦ •
◦ • ◦ • ◦ • ◦
• ◦ • ◦ • ◦ •
◦ • ◦ • ◦ • ◦
• ◦ • ◦ • ◦ •

3 black and 3 white queens on a 7 x 7 board:
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
B ◦ • ◦ • ◦ •
◦ • W • ◦ • ◦
• ◦ • ◦ • ◦ •
◦ • ◦ • ◦ • ◦
• ◦ • ◦ • ◦ •

4 black and 4 white queens on a 7 x 7 board:
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
• ◦ • ◦ • ◦ •
◦ • ◦ • ◦ • ◦
• ◦ • ◦ • ◦ •

5 black and 5 white queens on a 7 x 7 board:
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
B ◦ • ◦ • ◦ •
◦ • W • ◦ • ◦
• ◦ • ◦ • ◦ •

6 black and 6 white queens on a 7 x 7 board:
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
B ◦ • ◦ B ◦ •
◦ • W • ◦ • W
• ◦ • ◦ • ◦ •

7 black and 7 white queens on a 7 x 7 board:
• B • ◦ • B •
◦ B ◦ • B • ◦
• B • ◦ • B •
◦ • ◦ • B • ◦
W ◦ W ◦ • ◦ W
◦ • ◦ W ◦ • ◦
W ◦ W W • ◦ • </pre>


=={{header|Perl}}==
=={{header|Perl}}==
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W---W
W---W
</pre>
</pre>

=={{header|Phix}}==
=={{header|Phix}}==
{{trans|Go}}
{{trans|Go}}
Retrieved from "https://rosettacode.org/wiki/Peaceful_chess_queen_armies"