Dynamic Declaration Language (DDL)
Time Limit: 2 Seconds
Memory Limit: 65536 KB
DDL is a very simple programming language in which variables are dynamically declared
at run time. All variables in DDL are of the signed integer type within the range
-9999...9999. There are up to five types of statements in a DDL program (each
statement is in a separate program line, and the first statement is in line 1):
1. Dcl <id>
Dcl is a keyword specifying a declaration statement. id is a single (case-sensitive)
letter designating a DDL variable. For example Dcl x when executed correctly,
allocates memory for variable x, and sets its value to zero.
2. <id> = <ic>
This is an assignment statement, where id is a DDL variable, and ic is a literal
integer constant in the range (0...9999). For example x = 2000 when executed
correctly, changes value of x to 2000. Note that there may be one or more number
of blank characters around =, but there is no tab characters.
3. Goto <label>, or Goto <id> <label>
Goto is a keyword specifying an unconditional or conditional goto statement.
label is a program line's number. For example Goto 5 transfers the program execution
flow to line 5 of the program, and
Goto x 5 when executed correctly, trasfers the flow to line 5 iff x>0, and
to the next line otherwise. The label is guaranteed to be in the range of program
4.Inc <id>, or Dec <id>
Inc and Dec are keywords specifying increment and decrement statements respectively.
For example Inc x (Dec y) when executed correctly adds (substracts) 1 to (from)
the value of x (y).
End is a keyword specifying the end statement, whose execution stops the program.
Not that the keywords of the DDL language are case-insensitive.
When one of the following erroneous statements encounters during the program
execution, an error message appears in a separate line of the output. Each error
message is of the form <label> <space> <error code>. label
is the line number for the erroneous statement, space is one blank character,
and error code is a positive integer specified below.
1. Dcl x is erroneous if x has not been referenced (used in assignment, goto,
increment or decrement) since the last time a Dcl x (declaring the same variable)
statement has been executed, unless this is the first Dcl x statement being
executed. In this erroneous condition, an error message indicating a repeated
declaration is generated as <label> 1, where label is the program line
number for the erroneous statement. Then the program flow transfers to the statement
in the next program line, and any prior correctly executed declaration for x
2.Any other statement where a variable such as x is referenced (used in assignment,
goto, increment or decrement) is erroneous if no Dcl x has been previously correctly
executed. In this case, an error message indicating an undeclared reference
is generated as <label> 2 and the program execution continues from the
First line of the input file contains a single integer N indicating the number
of DDL programs to follow (1 <= N <= 20). The first line of each test
case contains a single integer indicating number of statements in that program
which is in the range (1...100). There are no blank lines between test cases.
Statements of each DDL program come one after the other in separate lines without
any blank lines in between. Statements are not explicitly labeled, but they
are implicitly labeled by the number of their line beginning from 1 for the
first statement in each program. There is no syntax error in programs and they
are guaranteed to terminate, and no overflow or underflow errors will occur
during execution. In each line of the program, tokens (e.g. GOTO, =, etc.) are
separated by at least one blank character. Also there may be some blank characters
in the beginning or at the end of each line.
For each input DDL program, your output should start with the program number
in the first line, followed by the error messages generated by the program in
the order they are generated, each error message in one line. There should be
no blank lines between error messages.
GOTO X 5
Y = 100
Y = 50
Source: Asia 2000, Tehran (Iran)