Data commit

Task/N-queens-problem/BBC-BASIC/n-queens-problem.basic

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+      Size% = 8
+      Cell% = 32
+      VDU 23,22,Size%*Cell%;Size%*Cell%;Cell%,Cell%,16,128+8,5
+      *font Arial Unicode MS,16
+      GCOL 3,11
+      FOR i% = 0 TO Size%-1 STEP 2
+        RECTANGLE FILL i%*Cell%*2,0,Cell%*2,Size%*Cell%*2
+        RECTANGLE FILL 0,i%*Cell%*2,Size%*Cell%*2,Cell%*2
+      NEXT
+      num% = FNqueens(Size%, Cell%)
+      SYS "SetWindowText", @hwnd%, "Total " + STR$(num%) + " solutions"
+      REPEAT : WAIT 1 : UNTIL FALSE
+      END
+
+      DEF FNqueens(n%, s%)
+      LOCAL i%, j%, m%, p%, q%, r%, a%(), b%(), c%()
+      DIM a%(n%), b%(n%), c%(4*n%-2)
+      FOR i% = 1 TO DIM(a%(),1) : a%(i%) = i% : NEXT
+      m% = 0
+      i% = 1
+      j% = 0
+      r% = 2*n%-1
+      REPEAT
+        i% -= 1
+        j% += 1
+        p% = 0
+        q% = -r%
+        REPEAT
+          i% += 1
+          c%(p%) = 1
+          c%(q%+r%) = 1
+          SWAP a%(i%),a%(j%)
+          p% = i% - a%(i%) + n%
+          q% = i% + a%(i%) - 1
+          b%(i%) = j%
+          j% = i% + 1
+        UNTIL j% > n% OR c%(p%) OR c%(q%+r%)
+        IF c%(p%)=0 IF c%(q%+r%)=0 THEN
+          IF m% = 0 THEN
+            FOR p% = 1 TO n%
+              MOVE 2*s%*(a%(p%)-1)+6, 2*s%*p%+6
+              PRINT "♛";
+            NEXT
+          ENDIF
+          m% += 1
+        ENDIF
+        j% = b%(i%)
+        WHILE j% >= n% AND i% <> 0
+          REPEAT
+            SWAP a%(i%), a%(j%)
+            j% = j%-1
+          UNTIL j% < i%
+          i% -= 1
+          p% = i% - a%(i%) + n%
+          q% = i% + a%(i%) - 1
+          j% = b%(i%)
+          c%(p%) = 0
+          c%(q%+r%) = 0
+        ENDWHILE
+      UNTIL i% = 0
+      = m%