OGE Informatics: Programming and Algorithm Execution

Core ideas

Questions present short programs or pseudocode and ask for the output. You must understand variables and types (integer, real, string, boolean), assignment, arithmetic operators (including integer division div/// and remainder mod/%), comparison and logic, and arrays with indexing. Control flow: sequence, conditionals, loops, and simple subroutines.

Traps to watch

• Integer vs. real division: 7 / 2 may be 3.5 or 3 depending on type; 7 mod 2 is 1.
• Array indices: know whether the first index is 0 or 1 in the given language/pseudocode.
• String concatenation vs. numeric addition: "2" + 3 may give "23".
• Operator precedence: and/or and comparison order; use parentheses mentally.
• Off-by-one in loop bounds and in for i = a to b (inclusive).

Rule of thumb

Execute the program exactly as written, line by line, tracking every variable. Do not "optimize" or assume intent - the machine does what is written.

Worked example

x = 10
y = 3
q = x div y
r = x mod y
print q, r

10 div 3 = 3, 10 mod 3 = 1, so output is 3 1. If a student computes 10/3 = 3.33, they have used real division and will pick the wrong option.