GATE CS 2017 Set 1 — Question 43
Go beyond PYQs with Success TrackerAI-powered personalised practice and doubt support. Unlimited practice on eligible plans; AI usage limits apply.NAT+2 / -0MediumBasic Blocks & Flow GraphsCode OptimizationCompiler DesignControl FlowC ProgrammingProgramming & Data Structures
Compiler Design → Code Optimization → Basic Blocks & Flow Graphs
Last updated
Question
Consider the following grammar:where relop is a relational operator (e.g., <, >, ...),
stmt -> if expr then expr else expr; stmt | ε
expr -> term relop term | term
term -> id | number
id -> a | b | c
number -> [0-9]
ε refers to the empty statement, and if, then, else are terminals.Consider a program following the above grammar containing ten if terminals. The number of control flow paths in is _______. For example, the programif e1 then e2 else e3has 2 control flow paths, and .Correct answer
1024 to 1024
Solution
The productiongenerates a sequence of if-then-else statements, one after another, ending with the empty statement . Every statement contains exactly one if, and there is no nesting (the
then and else parts are expressions, not statements).So a program with ten if terminals is a sequence of 10 if-then-else statements.- Each if-then-else has 2 control flow paths: condition → then-part, or condition → else-part.
- After either branch control reaches the next statement, so the choices in different statements are independent.
Continue learning with Success Tracker
A step still unclear? Work through it with support
Use Success Tracker to ask about the reasoning, then try another GATE CS question to check your understanding.
AI-powered practice· Unlimited practice on eligible plans
- PYQs with solutions
- Attempt available previous-year questions, then compare your reasoning with the worked solution. Coverage varies by stream.
- Practice that adapts
- Choose a topic, work on weaker areas and bookmark questions to revisit. Your attempts feed your progress tracking.
- AI doubt support
- Ask follow-up questions about a step or concept while practising, instead of stopping at the final answer.
Unlimited practice is available on eligible plans. Free practice and AI usage have limits; check the current plan allowances before choosing.
This page stays readable without an account. AI responses can be wrong; check them against the solution and source material.
More questions on Code Optimization
2026 Set 2 Q12The set T represents various traversals over binary tree. The set S represents the order of…2026 Set 2 Q17In C runtime environment, which one of the following is stored in heap?2026 Set 2 Q19Consider the following three ANSI-C programs, P1, P2, and P3. P1 [code] P2 [code] **P3**…2026 Set 1 Q23Let be an odd number greater than 100. Consider a binary minheap with elements stored in an…2026 Set 1 Q24Consider a hash table that is initially empty. The hash table is maintained…