Initial data commit

Task/Sorting-algorithms-Heapsort/BBC-BASIC/sorting-algorithms-heapsort.basic

@@ -0,0 +1,35 @@
+      DIM test(9)
+      test() = 4, 65, 2, -31, 0, 99, 2, 83, 782, 1
+      PROCheapsort(test())
+      FOR i% = 0 TO 9
+        PRINT test(i%) ;
+      NEXT
+      PRINT
+      END
+
+      DEF PROCheapsort(a())
+      LOCAL e%
+      PROCheapify(a())
+      FOR e% = DIM(a(),1) TO 1 STEP -1
+        SWAP a(e%), a(0)
+        PROCsiftdown(a(), 0, e%-1)
+      NEXT
+      ENDPROC
+
+      DEF PROCheapify(a())
+      LOCAL s%, m%
+      m% = DIM(a(),1)
+      FOR s% = (m% - 1) / 2 TO 0 STEP -1
+        PROCsiftdown(a(), s%, m%)
+      NEXT
+      ENDPROC
+
+      DEF PROCsiftdown(a(), s%, e%)
+      LOCAL c%, r%
+      r% = s%
+      WHILE r% * 2 + 1 <= e%
+        c% = r% * 2 + 1
+        IF c% + 1 <= e% IF a(c%) < a(c% + 1) c% += 1
+        IF a(r%) < a(c%) SWAP a(r%), a(c%) : r% = c% ELSE ENDPROC
+      ENDWHILE
+      ENDPROC