/acsl-wdtpd-interpreter

An interpreter for the programming language featured in ACSL's "What Does this Program Do" questions

Primary LanguageJavaScript

ACSL "What Does This Program Do" Interpreter

Demo

Interpreter for the pseudocode used in American Computer Science League competitions in contest 1.

Features

These are the full capabilities of the language as defined by the ACSL wiki

Construct Code Segment
Operators ! (not), ^ or ↑(exponent), *, / (real division), % (modulus), +, -, >, <, >=, <=, !=, ==, && (and), || (or) in that order of precedence
Functions abs(x) - absolute value, sqrt(x) - square root, int(x) - greatest integer <= x
Variables Start with a letter, only letters and digits
Sequential statements INPUT variable
variable = expression (assignment)
OUTPUT variable
Decision statements IF boolean expression THEN
Statement(s)
ELSE (optional)
Statement(s)
END IF
Indefinite Loop statements WHILE boolean expression
Statement(s)
END WHILE
Definite Loop statements FOR variable = start TO end STEP increment
Statement(s)
NEXT
Arrays: 1 dimensional arrays use a single subscript such as A(5). 2 dimensional arrays use (row, col) order such as A(2,3). Arrays can start at location 0 for 1 dimensional arrays and location (0,0) for 2 dimensional arrays. Most ACSL past problems start with either A(1) or A(1,1). The size of the array will usually be specified in the problem statement.
Strings: Basically python strings

And here's more features found in practice problems that they failed to mention in their wiki:

Construct Code Segment
Alternate Decision Statement Syntax IF expression THEN Statement ELSE Statement
(one line)
Program Early Termination END

Example Code Snippets

input H, R
B = 0
if H>48 then
    B = B + (H - 48) * 2 * R
    H = 48
end if
if H>40 then
   B = B + (H - 40) * (3/2) * R
   H = 40
end if
B = B + H * R
output B

A = "BANANAS"
NUM = 0: T = ""
for J = len(A) - 1 to 0 step -1
     T = T + A[j]
next 
for J = 0 to len(A) - 1
    if A[J] == T[J] then NUM = NUM + 1
next

A(0) = 12: A(1) = 41: A(2) = 52
A(3) = 57: A(4) = 77: A(5) = -100
B(0) = 17: B(1) = 34: B(20) = 81
J = 0: K = 0: N = 0
while A(J) > 0
  while B(K) <= A(J)
    C(N) = B(K)
    N = N + 1
    k = k + 1
  end while
  C(N) = A(J): N = N + 1: J = J + 1
end while
C(N) = B(K)