Computer Science Previous Year Questions (page 11)

Explanation

Kruskal's algorithm picks edges in increasing order of weight while avoiding cycles: GC = 2, AD = 2, GB = 3, GA = 3, then BF = 4 and AE = 4. So the order is GC, AD, GB, GA, BF, AE. Note: more than one order is possible since edge weights are repeated.

Explanation

With distinct edge weights the MST is unique and always contains Eₘᵢₙ. Eₘₐₓ can be in the MST (when it is a bridge, its removal disconnects G), so the statement "No minimum spanning tree contains Eₘₐₓ" is false.

Explanation

Scalability is the ability of a process, network, software or organization to grow and manage increased demand. A scalable system can adapt to the changing needs of its users.

Explanation

To minimise access time on a sequential device, store files in increasing order of size: F4 (60 KB), F6 (65 KB), F3 (75 KB), F1 (150 KB), F2 (225 KB), F5 (275 KB).

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The dispatcher is the module that gives control of the CPU to the process selected by the short-term scheduler.

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Wait & signal operations are the two atomic operations performed on a semaphore.

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Relations are decomposed into normal forms (normalization) to prevent insertion, deletion and update anomalies.

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As keyed by the book, MODIFY is the SQL command that changes one or more fields in a record.

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A view is a virtual table through which a selective portion of the data from one or more tables can be seen; it does not contain data of its own. A stored procedure executed when an event occurs is a trigger, not a view. So only (B) is true.

Explanation

AVG returns the average of the values in a group, ignoring null values. It is an aggregate function. Syntax: AVG([ALL | DISTINCT] expression).

Explanation

Entity integrity - no duplicate rows in a table (iv); Domain integrity - enforces valid entries for a column (iii); Referential integrity - rows can't be deleted which are used by other records (ii); User defined integrity - enforces specific business rules that do not fall into entity or domain integrity (i).

Explanation

Non-adaptive (static) routing algorithms do not base their routing decisions on measurements or estimates of the current traffic and topology. Instead, the route from one node to another is computed in advance.

Explanation

The transport layer is responsible for end-to-end communication over a network; it provides logical communication between application processes running on different hosts.

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Switch takes data sent from one network device & forwards it to the destination node based on MAC address. A switch is a multi port bridge with a buffer and a design that can boost its efficiency and performance. Switch is data link layer device. It can perform error checking before forwarding data.

Explanation

Gigabit Ethernet uses the standard Ethernet frame, whose destination and source address (MAC address) fields are each 48 bits long.

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The address 0.0.0.0 is used by a host as its source address while it is booting (e.g. in a DHCP request) before it knows its own IP address.

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As software is used, it receives multiple change requests; each change can introduce errors in component interactions, so the software deteriorates over time.

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Software re-engineering is a process of software development which is done to improve the maintainability of a software system.

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Agile philosophy stresses self-organizing teams, collaboration with customers, welcoming change and rapid delivery of working software. Testing is done continuously along with development, not as a separate phase after the build phase.

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Traditional testing starts with unit testing, followed by integration testing, then system testing and finally validation (acceptance) testing: (C), (A), (B), (D).

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Regression testing verifies that previously developed and tested software still performs correctly after it has been changed, e.g. after enhancements or patches during maintenance.

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A virtual function cannot be static, because a virtual function is a non-static member function whose call is resolved through a specific object at run time.

Explanation

Function templates are instantiated implicitly when the function is called with arguments, whereas class templates are instantiated by defining an object with explicit template arguments. So class templates and function templates are not instantiated in the same way; statement (a) is not correct.

Explanation

Only array element access ([]) is left-to-right associative among the options listed. All others are unary operators and are right-to-left associative.

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A member function can always access all the data (public, private and protected) of the class of which it is a member.

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Postfix ++ has higher precedence than *, so *ptrdata++ is evaluated as *(ptrdata++): the value at ptrdata is used and then the pointer moves to the next location. (*ptrdata)++ would instead increment the value stored at that location.

Explanation

As keyed by the book, Bluetooth (in its low-energy form) consumes the least power among the options; Wi-Fi and GSM/CDMA consume much more.

Explanation

The parser (syntax analyzer) recognizes syntax (A-iii); the scanner (lexical analyzer) turns the character stream into words/tokens (B-iv); the semantic analyzer checks meanings and consistent use of names (C-ii); the optimizer is an IR-to-IR transformer that improves the IR program (D-i).

Explanation

Sunway TaihuLight was named the world's fastest supercomputer in the TOP500 list at that time. It was developed by China's National Research Center of Parallel Computer Engineering & Technology (NRCPC).

Explanation

ERP software packages are themselves combinations of separate applications for manufacturing, materials resource planning, general ledger, human resources, procurement and order entry.

Explanation

K-means, self-organizing feature maps and agglomerative methods are clustering methods. The k-nearest neighbour (K-NN) algorithm is a non-parametric method used for classification and regression, not clustering.

Explanation

Odd binary numbers end with 1 in the LSB and even numbers end with 0. Only 0*1*0*1+ always ends with at least one 1, so its language contains no even values.

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F1, F2, F3 each with 7 micro-operations need 3 bits each = 9 bits; CD for 4 status bits needs 2 bits; BR with 4 options needs 2 bits; ADF for 128 locations needs 7 bits. Total = 9 + 2 + 2 + 7 = 20 bits.

Explanation

The isolated I/O method isolates memory and I/O addresses so that the memory address range is not affected by interface address assignment. Memory-mapped I/O uses the same address space for memory and I/O devices. In asynchronous serial transfer the two units do not share a common clock; in synchronous serial transfer they do.

Explanation

AC is the auxiliary carry flag, CY is the carry flag and Z is the zero flag. All these flags are affected by arithmetic operations.

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The 8085 microprocessor has a 16-bit address bus, so 2¹⁶ = 65,536 different memory locations can be addressed.

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The ALU forms the processing unit (A-iii); timing and control belongs to the instruction unit (B-iv); the general-purpose registers are in the storage and interface unit (C-ii).

Explanation

Indexed addressing mode is best suited for accessing an array in contiguous memory location.

Explanation

For a full binary tree with n internal nodes, e = i + 2n. Example: a full binary tree with 7 internal nodes of depth up to 2 has i = 0 + 1×2 + 2×4 = 10 and 8 leaves at depth 3, so e = 24 = 10 + 2×7.

Explanation

Standard planning algorithms assume the environment to be both deterministic and fully observable.

Explanation

In the worst case greedy (best-first) search keeps all generated nodes in memory. With branching factor b and maximum depth m, the space complexity is O(bᵐ).

Explanation

Heap allocation is required for languages that support dynamic data structures, whose storage is allocated and freed at run time in an arbitrary order.

Explanation

Scaling by 3 units in x' and 4 units in y' gives x = x'/3 and y = y'/4. Substituting in x² + y² = 1 gives (x'/3)² + (y'/4)² = 1.

Explanation

Window: xwmin = 1, ywmin = 1, xwmax = 3, ywmax = 5. Viewport (normalized screen): xvmin = 0, yvmin = 0, xvmax = 1, yvmax = 1. Scale factors sx = (1 − 0)/(3 − 1) = 1/2 and sy = (1 − 0)/(5 − 1) = 1/4. N = T(xvmin, yvmin) · S(sx, sy) · T(−xwmin, −ywmin), which gives the matrix [1/2 0 −1/2], [0 1/4 −1/4], [0 0 1].

Explanation

The producer-consumer (bounded buffer) problem describes two processes, the producer and the consumer, which share a common fixed-size buffer used as a queue. The producer puts items into the buffer and waits if it is full; the consumer removes items and waits if it is empty.

Explanation

In statement set (A), the many-to-one model maps many user threads to one kernel thread, the one-to-one model maps one user thread to one kernel thread, and the many-to-many model maps many user threads to a smaller or equal number of kernel threads; all are true. Set (B) reverses the roles of user and kernel threads, so it is false.

Explanation

For this reference string with 3 frames, the optimal algorithm gives 9 page faults, fewer than FIFO, LIFO or LRU. So the optimal algorithm has the minimum number of page faults.

Explanation

UNIX provides read, write and execute permissions on files, and three sets of permissions: for the owner, for the group and for others. So both (A) and (B) are true.