Data commit

Task/N-queens-problem/FreeBASIC/n-queens-problem-1.basic

@@ -0,0 +1,56 @@
+' version 13-04-2017
+' compile with: fbc -s console
+Dim Shared As ULong count, c()
+
+Sub n_queens(row As ULong, n As ULong, show As ULong = 0)
+
+    Dim As ULong x, y
+
+    For x = 1 To n
+
+        For y = 1 To row -1
+            If c(y) = x OrElse ((row - y) - Abs(x - c(y))) = 0 Then
+                Continue For, For
+            End If
+        Next
+
+        c(row) = x
+        If row < n Then
+            n_queens(row +1 , n, show)
+        Else
+            count += 1
+
+            If show <> 0 Then
+                For y = 1 To n
+                    Print Using "###"; c(y);
+                Next
+                Print
+            End If
+
+        End If
+
+    Next
+
+End Sub
+
+' ------=< MAIN >=------
+
+Dim As ULong n = 5
+ReDim c(n)
+' n_queens(1, n, show = 0 only show total | show <> 0 show every solution
+n_queens(1, n, 1)
+Print Using "## x ## board, ##### solutions"; n; n; count
+Print
+
+For n = 1 To 14
+    ReDim c(n)
+    count = 0
+    n_queens(1, n)
+    Print Using "A ## x ## board has ######## solutions"; n; n; count
+Next
+
+' empty keyboard buffer
+While Inkey <> "" : Wend
+Print : Print "hit any key to end program"
+Sleep
+End

Task/N-queens-problem/FreeBASIC/n-queens-problem-2.basic

@@ -0,0 +1,41 @@
+Sub aux(n As Integer, i As Integer, a() As Integer, _
+        u() As Integer, v() As Integer, ByRef m As LongInt)
+
+    Dim As Integer j, k, p, q
+    If i > n Then
+        m += 1
+        For k = 1 To n : Print a(k); : Next : Print
+    Else
+        For j = i To n
+            k = a(j)
+            p = i - k + n
+            q = i + k - 1
+            If u(p) And v(q) Then
+                u(p) = 0 : v(q) = 0
+                a(j) = a(i) : a(i) = k
+                aux(n, i + 1, a(), u(), v(), m)
+                u(p) = 1 : v(q) = 1
+                a(i) = a(j) : a(j) = k
+            End If
+        Next
+    End If
+End Sub
+
+Dim As Integer n, i
+Dim m As LongInt = 1
+If Command(1) <> "" Then
+    n = CInt(Command(1))
+    ReDim a(1 To n) As Integer
+    ReDim u(1 To 2 * n - 1) As Integer
+    ReDim v(1 To 2 * n - 1) As Integer
+    For i = 1 To n
+        a(i) = i
+    Next
+    For i = 1 To 2 * n - 1
+        u(i) = 1
+        v(i) = 1
+    Next
+    m = 0
+    aux(n, 1, a(), u(), v(), m)
+    Print m
+End If

Task/N-queens-problem/FreeBASIC/n-queens-problem-3.basic

@@ -0,0 +1,43 @@
+Dim As Integer n, i, j, k, p, q
+Dim m As LongInt = 0
+
+If Command(1) <> "" Then
+    n = CInt(Command(1))
+    ReDim a(1 To n) As Integer
+    ReDim s(1 To n) As Integer
+    ReDim u(1 To 2 * n - 1) As Integer
+    ReDim v(1 To 2 * n - 1) As Integer
+    For i = 1 To n
+        a(i) = i
+    Next
+    For i = 1 To 2 * n - 1
+        u(i) = 1
+        v(i) = 1
+    Next
+    m = 0
+    i = 1
+L1: If i > n Then
+        m += 1
+        For k = 1 To n : Print a(k); : Next : Print
+        Goto L4
+    End If
+    j = i
+L2: k = a(j)
+    p = i - k + n
+    q = i + k - 1
+    If u(p) And v(q) Then
+        u(p) = 0 : v(q) = 0
+        a(j) = a(i) : a(i) = k
+        s(i) = j
+        i += 1
+        Goto L1
+    End If
+L3: j += 1 : If j <= n Goto L2
+L4: i -= 1 : If i = 0 Then Print m : End
+    j = s(i)
+    k = a(i) : a(i) = a(j) : a(j) = k
+    p = i - k + n
+    q = i + k - 1
+    u(p) = 1 : v(q) = 1
+    Goto L3
+End If