20+ HMEL's Guru Gobind Singh Petroleum Refinery Interview Questions and Answers

Find the duplicate number in an array of integers from 0 to N-2.

• Iterate through the array and keep track of the frequency of each number using a hashmap.

• Return the number with a frequency greater than 1 as the duplicate number.

• Alternatively, use Floyd's Tortoise and Hare algorithm to find the duplicate number in O(N) time and O(1) space.

Count the total number of inversions in an integer array.

• Iterate through the array and for each pair of elements, check if the conditions for inversion are met.

• Use a nested loop to compare each pair of elements efficiently.

• Keep a count of the inversions found and return the total count at the end.

Create a function to remove all occurrences of a given character from a string.

• Iterate through the string and build a new string excluding the specified character.

• Use string manipulation functions to achieve the desired result.

• Handle the case where the character does not exist in the string.

• Return the modified string as the output.

Develop a function to remove all instances of a given character from a string.

• Iterate through the string and only add characters that are not equal to the given character to a new string.

• Return the new string as the result.

• Handle edge cases like empty string or character not found in the string.

• Example: Input 'hello world' and 'o', output 'hell wrld'.

The task is to find the frequency of each character from 'a' to 'z' in a given string.

• Create an array of size 26 to store the frequency of each character from 'a' to 'z'.

• Iterate through the given string and increment the count of each character in the array.

• Print the array of frequencies as the output for each test case.

Return the middle element of a singly linked list, or the one farther from the head node in case of even number of elements.

• Traverse the linked list with two pointers, one moving twice as fast as the other

• When the fast pointer reaches the end, the slow pointer will be at the middle

• Return the element pointed to by the slow pointer

Given an array of integers, find a contiguous subarray with a given sum.

• Iterate through the array while keeping track of the current sum and start index.

• Use a hashmap to store the sum and its corresponding index.

• If the current sum - target sum exists in the hashmap, return the indices.

• Handle edge cases like when the target sum is 0 or when no subarray is found.

Find the sum of the subarray with the maximum sum among all subarrays in a given array.

• Iterate through the array and keep track of the maximum sum subarray seen so far.

• Use Kadane's algorithm to efficiently find the maximum subarray sum.

• Handle cases where all elements are negative or array is empty.

• Example: For input arr = [-2, 1, -3, 4, -1], the maximum subarray sum is 4.

Find the node where two linked lists merge, return -1 if no merging occurs.

• Traverse both lists to find their lengths and the difference in lengths

• Move the pointer of the longer list by the difference in lengths

• Traverse both lists simultaneously until they meet at the merging point

Method overloading is having multiple methods in the same class with the same name but different parameters. Method overriding is redefining a method in a subclass with the same signature as in the superclass.

• Method overloading allows multiple methods with the same name but different parameters in the same class.

• Method overriding involves redefining a method in a subclass with the same signature as in the superclass.

• Method overloading is resolved at compile time based on the ...read more

I am highly adaptable to changes in technology and have a structured learning process to ensure smooth knowledge transfer.

• I stay up-to-date with the latest technology trends and advancements

• I am open to learning new technologies and tools

• I have a structured learning process that involves researching, reading documentation, and practicing

• I collaborate with team members to share knowledge and learn from each other

• I attend conferences and workshops to learn about new technologie...read more

Static linking includes all library modules in the executable file, while dynamic linking loads libraries at runtime.

• Static linking includes all library modules in the executable file, increasing its size.

• Dynamic linking loads libraries at runtime, reducing the size of the executable file.

• Static linking results in faster startup time, while dynamic linking allows for easier updates to libraries.

• Examples of static linking include linking libraries during compilation, while dyn...read more

Inline functions are actual functions while macros are preprocessor directives in C++.

• Inline functions are actual functions defined with the 'inline' keyword, while macros are preprocessor directives that are replaced before compilation.

• Inline functions provide type checking and scope resolution, while macros do not.

• Inline functions can have multiple lines of code and can access variables in the scope they are called from, while macros are limited to a single line and do not ...read more

UNION combines and removes duplicate rows, UNION ALL combines without removing duplicates.

• UNION combines the result sets of two or more SELECT statements into a single result set

• UNION removes duplicate rows from the result set

• UNION ALL combines the result sets without removing duplicates

• UNION is slower than UNION ALL as it requires additional processing to remove duplicates

• Use UNION when you want to combine and remove duplicates, use UNION ALL when you want to combine without...read more

Multitasking involves executing multiple tasks simultaneously, while multiprogramming involves running multiple programs on a single processor.

• Multitasking allows multiple tasks to run concurrently on a single processor, switching between them quickly.

• Multiprogramming involves loading multiple programs into memory and executing them concurrently, utilizing idle CPU time efficiently.

• Examples of multitasking include running multiple applications on a computer at the same time, ...read more

A process is an executing instance of a program, while a program is a set of instructions stored in the computer's memory.

• A program is a static set of instructions stored on disk, while a process is a dynamic instance of those instructions being executed in memory.

• Multiple processes can be running the same program simultaneously, each with its own memory space and resources.

• Processes have their own unique process ID (PID) and can communicate with each other through inter-proc...read more

Virtual functions in C++ allow a function to be overridden in a derived class, enabling polymorphic behavior.

• Virtual functions are declared in a base class with the 'virtual' keyword.

• They are overridden in derived classes to provide specific implementations.

• They enable polymorphism, allowing objects of different derived classes to be treated as objects of the base class.

• Example: class Animal { virtual void makeSound() { cout << 'Animal sound'; } }; class Dog : public Animal {...read more

ITIL is a framework for IT service management that helps in application management practices.

• ITIL stands for Information Technology Infrastructure Library.

• It provides a set of best practices for IT service management.

• ITIL helps in improving the quality of IT services and reducing costs.

• It includes processes for incident management, problem management, change management, and more.

• ITIL helps in aligning IT services with business needs.

• In application management, ITIL helps in en...read more

A process is an instance of a program, while a thread is a unit of execution within a process.

• A process has its own memory space, while threads share the same memory space.

• Processes are independent and isolated, while threads can communicate and share resources.

• Creating a new process is more resource-intensive than creating a new thread.

• Processes have their own program counter, while threads share the same program counter.

• Examples: Running multiple instances of a web browser ...read more

A linker error in C++ occurs when the linker is unable to resolve references to functions or variables during the linking phase of compilation.

• Linker errors occur when there are missing definitions for functions or variables that are referenced in the code.

• Common causes of linker errors include forgetting to define a function that is declared, or not including the necessary library or object files.

• Example: If a function 'foo()' is declared in a header file but not defined in ...read more

Views provide a virtual representation of data, offering advantages such as simplifying complex queries, enhancing security, and improving performance.

• Views simplify complex queries by predefining commonly used joins, filters, and aggregations.

• Views enhance security by allowing users to access only specific columns or rows of a table.

• Views improve performance by storing the results of complex queries, reducing the need for repetitive calculations.

• Views can be used to hide sen...read more

ARP stands for Address Resolution Protocol, used to map IP addresses to MAC addresses in a local network.

• ARP is used to find the MAC address of a device based on its IP address

• It operates at the data link layer of the OSI model

• ARP requests are broadcasted to all devices on the local network

• Example: When a device wants to communicate with another device on the same network, it uses ARP to find the MAC address of the destination device