tasks a-s

Task/N-queens-problem/Lua/n-queens-problem.lua

@@ -0,0 +1,46 @@
+N = 8
+
+board = {}
+for i = 1, N do
+    board[i] = {}
+    for j = 1, N do
+	board[i][j] = false
+    end
+end
+
+function Allowed( x, y )
+    for i = 1, x-1 do
+	if ( board[i][y] ) or ( i <= y and board[x-i][y-i] ) or ( y+i <= N and board[x-i][y+i] ) then
+  	    return false
+	end
+    end		
+    return true
+end
+
+function Find_Solution( x )
+    for y = 1, N do
+	if Allowed( x, y ) then
+  	    board[x][y] = true
+	    if x == N or Find_Solution( x+1 ) then
+		return true
+	    end
+	    board[x][y] = false			
+	end		
+    end
+    return false
+end
+		
+if Find_Solution( 1 ) then
+    for i = 1, N do
+ 	for j = 1, N do
+  	    if board[i][j] then
+		io.write( "|Q" )
+	    else
+		io.write( "| " )
+	    end
+	end
+	print( "|" )
+    end
+else
+    print( string.format( "No solution for %d queens.\n", N ) )
+end