100 REM Dutch national flag problem
110 REM 0: blue, 1: while, 2: red
120 OPTION BASE 0
130 N% = 20
140 UP% = N% - 1
150 DIM T%(UP%)
160 REM Set colors
170 RANDOMIZE
180 FOR I% = 0 TO UP%
190  T%(I%) = INT(RND * 3)
200 NEXT I%
210 PRINT "Unsorted:"
220 GOSUB 1000
230 GOSUB 2000
240 PRINT
250 PRINT "Sorted:"
260 GOSUB 1000
270 END
1000 REM ** Print color sequence
1010 FOR I% = 0 TO UP%
1020  IF T%(I%) = 0 THEN PRINT "B"; ELSE IF T%(I%) = 1 THEN PRINT "W"; ELSE PRINT "R";
1030 NEXT I%
1040 PRINT
1050 RETURN
2000 REM ** Sort by color
2010 B% = 0: W% = 0: R% = UP%
2020 WHILE W% <= R%
2030  IF T%(W%) <> 1 THEN 2070
2040   REM white
2050   W% = W% + 1
2060   GOTO 2160
2070  IF T%(W%) <> 0 THEN 2130
2080   REM blue
2090   SWAP T%(B%), T%(W%)
2100   B% = B% + 1
2110   W% = W% + 1
2120   GOTO 2160
2130   REM red
2140   SWAP T%(W%), T%(R%)
2150   R% = R% - 1
2160 WEND
2170 RETURN