safe-code-analyzer/safe_codes/100 doors_103.txt

DIM doors%(100)
FOR pass% = 1 TO 100
    FOR door% = pass% TO 100 STEP pass%
        doors%(door%) = NOT doors%(door%)
    NEXT door%
NEXT pass%      
FOR door% = 1 TO 100
    IF doors%(door%) PRINT "Door " ; door% " is open"
NEXT door%