18 Collections & Iterators questions from the Rust bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
B.a growable, heap-allocated, contiguous sequence of values of a single type
C.a collection storing key-value pairs with average constant-time lookup via hashing
D.a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
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2. Which term means: "a growable, heap-allocated, contiguous sequence of values of a single type"?
Junior
A.Lazy evaluation
B.HashMap
C.String slice
D.Vec
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3. Which statement is correct?
Junior
A.Vec — a growable, heap-allocated, contiguous sequence of values of a single type
B.Vec — a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
C.Vec — a collection storing key-value pairs with average constant-time lookup via hashing
D.Vec — the property that an iterator chain does no work until a consuming operation drives it
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4. What is HashMap?
Junior
A.the property that an iterator chain does no work until a consuming operation drives it
B.a collection storing key-value pairs with average constant-time lookup via hashing
C.a growable, heap-allocated, contiguous sequence of values of a single type
D.the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
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5. Which term means: "a collection storing key-value pairs with average constant-time lookup via hashing"?
Junior
A.collect
B.Vec
C.Iterator adaptor
D.HashMap
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6. Which statement is correct?
Junior
A.HashMap — a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
B.HashMap — the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
C.HashMap — a collection storing key-value pairs with average constant-time lookup via hashing
D.HashMap — a growable, heap-allocated, contiguous sequence of values of a single type
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7. What is String slice?
Junior
A.a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
B.a growable, heap-allocated, contiguous sequence of values of a single type
C.a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
D.a collection storing key-value pairs with average constant-time lookup via hashing
Answer + AI explanation with Pro
8. Which term means: "a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes"?
Junior
A.collect
B.HashMap
C.String slice
D.Vec
Answer + AI explanation with Pro
9. Which statement is correct?
Junior
A.String slice — a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
B.String slice — a collection storing key-value pairs with average constant-time lookup via hashing
C.String slice — the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
D.String slice — a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
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10. What is Iterator adaptor?
Mid
A.a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
B.the property that an iterator chain does no work until a consuming operation drives it
C.the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
D.a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
Answer + AI explanation with Pro
11. Which term means: "a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet"?
Mid
A.Vec
B.Lazy evaluation
C.Iterator adaptor
D.String slice
Answer + AI explanation with Pro
12. Which statement is correct?
Mid
A.Iterator adaptor — a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
B.Iterator adaptor — a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
C.Iterator adaptor — the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
D.Iterator adaptor — a collection storing key-value pairs with average constant-time lookup via hashing
Answer + AI explanation with Pro
13. What is Lazy evaluation?
Mid
A.a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
B.a growable, heap-allocated, contiguous sequence of values of a single type
C.a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
D.the property that an iterator chain does no work until a consuming operation drives it
Answer + AI explanation with Pro
14. Which term means: "the property that an iterator chain does no work until a consuming operation drives it"?
Mid
A.Vec
B.HashMap
C.Lazy evaluation
D.String slice
Answer + AI explanation with Pro
15. Which statement is correct?
Mid
A.Lazy evaluation — the property that an iterator chain does no work until a consuming operation drives it
B.Lazy evaluation — a collection storing key-value pairs with average constant-time lookup via hashing
C.Lazy evaluation — a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
D.Lazy evaluation — the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
Answer + AI explanation with Pro
16. What is collect?
Mid
A.a growable, heap-allocated, contiguous sequence of values of a single type
B.the property that an iterator chain does no work until a consuming operation drives it
C.a collection storing key-value pairs with average constant-time lookup via hashing
D.the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
Answer + AI explanation with Pro
17. Which term means: "the consuming method that drains an iterator and gathers its items into a target container such as a vector or map"?
Mid
A.Vec
B.Iterator adaptor
C.Lazy evaluation
D.collect
Answer + AI explanation with Pro
18. Which statement is correct?
Mid
A.collect — a lazy method such as map or filter that wraps one iterator to produce another without consuming it yet
B.collect — a borrowed, immutable, UTF-8 view into string data, written &str, that does not own its bytes
C.collect — a growable, heap-allocated, contiguous sequence of values of a single type
D.collect — the consuming method that drains an iterator and gathers its items into a target container such as a vector or map
Answer + AI explanation with Pro
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