Consider the string “GATECSELECTURE” S1: “GATECSELECTURE” is a prefix of given…
Consider the string “GATECSELECTURE”
S1: “GATECSELECTURE” is a prefix of given string.
S2: “GATECSELECTURE” is a suffix of given string.
S3: “CSELECTURE” is a subsequence of given string.
S4: “GTCS” is a substring of given string.
Which of the above statement is/are FALSE?
Answer: B. Only S4 — A prefix of string s is any string obtained by removing zero or more symbols from the end of s. For example, GATE, GATECSE,GATECSELECTURE and ϵ are prefixes…
- A.
Only S1 and S2
- B.
Only S4
- C.
Only S3 and S4
- D.
Only S3
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Correct answer: B
A prefix of string s is any string obtained by removing zero or more symbols from the end of s. For example, GATE, GATECSE,GATECSELECTURE and ϵ are prefixes of GATECSELECTURE.
A suffix of string s is any string obtained by removing zero or more symbols from the beginning of s. For example, LECTURE, CSELECTURE,GATECSELECTURE and ϵ are suffixes of GATECSELECTURE.
Evaluation of each statement:
S1 — "GATECSELECTURE is a prefix": True. The given string equals "GATECSELECTURE", and a string is a prefix of itself.
S2 — "GATECSELECTURE is a suffix": True. For the same reason as S1, the whole string is also a suffix of itself.
S3 — "CSELECTURE is a subsequence": True. Those characters appear in order and in fact contiguously at positions 5–14, so it is a subsequence (and a substring).
S4 — "GTCS is a substring": False. While the letters G, T, C, S appear in that order as a subsequence (positions 1, 3, 5, 6), they do not appear contiguously, so "GTCS" is not a substring.
Conclusion: Only the statement that "GTCS is a substring" is false. Therefore the correct answer is the choice that says only S4 is false.