Initial data commit

Task/Huffman-coding/BBC-BASIC/huffman-coding.basic

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+      INSTALL @lib$+"SORTSALIB"
+      SortUp% = FN_sortSAinit(0,0) : REM Ascending
+      SortDn% = FN_sortSAinit(1,0) : REM Descending
+
+      Text$ = "this is an example for huffman encoding"
+
+      DIM tree{(127) ch&, num%, lkl%, lkr%}
+      FOR i% = 1 TO LEN(Text$)
+        c% = ASCMID$(Text$,i%)
+        tree{(c%)}.ch& = c%
+        tree{(c%)}.num% += 1
+      NEXT
+
+      C% = DIM(tree{()},1) + 1
+      CALL SortDn%, tree{()}, tree{(0)}.num%
+      FOR i% = 0 TO DIM(tree{()},1)
+        IF tree{(i%)}.num% = 0 EXIT FOR
+      NEXT
+      size% = i%
+
+      linked% = 0
+      REPEAT
+        C% = size%
+        CALL SortUp%, tree{()}, tree{(0)}.num%
+        i% = 0 : WHILE tree{(i%)}.lkl% OR tree{(i%)}.lkr% i% += 1 : ENDWHILE
+        tree{(i%)}.lkl% = size%
+        j% = 0 : WHILE tree{(j%)}.lkl% OR tree{(j%)}.lkr% j% += 1 : ENDWHILE
+        tree{(j%)}.lkr% = size%
+        linked% += 2
+        tree{(size%)}.num% = tree{(i%)}.num% + tree{(j%)}.num%
+        size% += 1
+      UNTIL linked% = (size% - 1)
+
+      FOR i% = size% - 1 TO 0 STEP -1
+        IF tree{(i%)}.ch& THEN
+          h$ = ""
+          j% = i%
+          REPEAT
+            CASE TRUE OF
+              WHEN tree{(j%)}.lkl% <> 0:
+                h$ = "0" + h$
+                j% = tree{(j%)}.lkl%
+              WHEN tree{(j%)}.lkr% <> 0:
+                h$ = "1" + h$
+                j% = tree{(j%)}.lkr%
+              OTHERWISE:
+                EXIT REPEAT
+            ENDCASE
+          UNTIL FALSE
+          VDU tree{(i%)}.ch& : PRINT "  " h$
+        ENDIF
+      NEXT
+      END