6 + Interview Questions in Uber Technical Interview Questions: Freshers and Experienced in Uber Interview Questions Page 1 InterviewSolution

1.	In operating systems, define spooling.
Answer» Spooling is the temporary storage of data so that it can be used and processed by a device, software, or system. Data is supplied to and stored in MEMORY or other volatile storage until it is required by a programme or computer for execution. SPOOL is an abbreviation for "Simultaneous Peripheral Operations Online." The spool is typically stored in physical memory, buffers, or interrupts for Input/Output devices on the computer. To process the spool in ascending order, the FIFO (first in, first out) approach is employed. Spooling is the process of gathering data from a large number of Input/Output processes and STORING it in a buffer. This buffer is a memory or hard disc area that Input/Output devices can access. In a distributed context, an operating system does the following: Controls data spooling for Input/Output devices with varying data access rates. Maintains the spooling buffer, which acts as a data holding space while the slower device catches up. The spooling procedure preserves parallel computing since a computer can perform Input/Output in parallel sequence. The computer can now read data from a tape, write data to disc, and print data to a tape printer all at the same time. Printing is the most visible application of spooling. Before being added to the printing queue, the PAPERS to be printed are held in the SPOOL. Several programmes can run and use the CPU during this period without having to wait for the printer to FINISH printing on each paper individually. Many additional features, such as defining priorities, receiving notifications when the printing process is complete, and selecting different types of paper to print on based on the user's preferences, can be added to the Spooling printing process. Useful Interview Resources Data Structures Interview Questions &AMP; Answers Algo Interview Questions Software Engineer Resume – Full Guide Technical Interview Questions: Complete List

1.

In operating systems, define spooling.

Answer»

Spooling is the temporary storage of data so that it can be used and processed by a device, software, or system. Data is supplied to and stored in MEMORY or other volatile storage until it is required by a programme or computer for execution. SPOOL is an abbreviation for "Simultaneous Peripheral Operations Online." The spool is typically stored in physical memory, buffers, or interrupts for Input/Output devices on the computer. To process the spool in ascending order, the FIFO (first in, first out) approach is employed. Spooling is the process of gathering data from a large number of Input/Output processes and STORING it in a buffer. This buffer is a memory or hard disc area that Input/Output devices can access. In a distributed context, an operating system does the following:

Controls data spooling for Input/Output devices with varying data access rates.
Maintains the spooling buffer, which acts as a data holding space while the slower device catches up.
The spooling procedure preserves parallel computing since a computer can perform Input/Output in parallel sequence. The computer can now read data from a tape, write data to disc, and print data to a tape printer all at the same time.

Printing is the most visible application of spooling. Before being added to the printing queue, the PAPERS to be printed are held in the SPOOL. Several programmes can run and use the CPU during this period without having to wait for the printer to FINISH printing on each paper individually. Many additional features, such as defining priorities, receiving notifications when the printing process is complete, and selecting different types of paper to print on based on the user's preferences, can be added to the Spooling printing process.

Useful Interview Resources

Data Structures Interview Questions &AMP; Answers
Algo Interview Questions
Software Engineer Resume – Full Guide
Technical Interview Questions: Complete List

Discussion

2.	What is Servlet Collaboration?
Answer» The PROCESS of COMMUNICATING information among the servlets of a Java web application is known as servlet collaboration. This enables data to be transmitted from one servlet to another via method invocations. Java's Servlet API (Application Programming Interface), which exposes TWO interfaces, is the primary method for ACHIEVING Servlet Collaboration. javax.servlet.RequestDispatcher javax.servlet.http.HttpServletResponse These two interfaces contain the approaches for achieving the purpose of servlet information exchange.

2.

What is Servlet Collaboration?

Answer»

The PROCESS of COMMUNICATING information among the servlets of a Java web application is known as servlet collaboration. This enables data to be transmitted from one servlet to another via method invocations. Java's Servlet API (Application Programming Interface), which exposes TWO interfaces, is the primary method for ACHIEVING Servlet Collaboration.

javax.servlet.RequestDispatcher
javax.servlet.http.HttpServletResponse

These two interfaces contain the approaches for achieving the purpose of servlet information exchange.

Discussion

3.

What is the difference between Swapping and Paging.

Answer»

The main differences between Swapping and PAGING are given below:

SWAPPING	PAGING
In swapping, the whole process in its entirety is moved to the secondary memory.	Paging is done when some part of a process is being transferred to secondary memory.
In Swapping, the temporary TRANSFER of a process from the main memory to secondary memory takes place.	In Paging, a contiguous block of memory is made non-contiguous but of FIXED SIZE called frame or pages.
Swapping requires no memory management.	Paging requires non-contiguous Memory Management.
The direction regarding the solution in it is provided in swapping.	No direction regarding the solution in it is provided in Paging.

Discussion

4.	Write functional code for solving the problem given below: Detect whether or not a given linked list contains a cycle.
Answer» C ++ function which solves the given Data STRUCTURES and Algorithm problem is given below: bool detectCycle(ListNode* root){ ListNode slow = root, fast = root; while (slow && fast && fast -> link) { slow = slow->link; fast = fast->link->link; if (slow == fast) { return true; } } return false;} For solving this question, we can use Floyd's Approach to Find cycle in a linked list. It is stated below: Two POINTERS are used for TRAVERSING the linked list. One pointer (slow) should be moved by one, while another pointer (fast) should be moved by two. There is a loop if these points intersect at the same node. A linked list does not have a loop if the pointers do not MEET.

4.

Write functional code for solving the problem given below: Detect whether or not a given linked list contains a cycle.

Answer»

C ++ function which solves the given Data STRUCTURES and Algorithm problem is given below:

bool detectCycle(ListNode* root){ ListNode *slow = root, *fast = root; while (slow && fast && fast -> link) { slow = slow->link; fast = fast->link->link; if (slow == fast) { return true; } } return false;}

For solving this question, we can use Floyd's Approach to Find cycle in a linked list. It is stated below:

Two POINTERS are used for TRAVERSING the linked list.
One pointer (slow) should be moved by one, while another pointer (fast) should be moved by two.
There is a loop if these points intersect at the same node. A linked list does not have a loop if the pointers do not MEET.

Discussion

5.	Write functional code for solving the problem given below:
Answer» Return the result of a sequence of enqueue and dequeue actions without utilising a queue data structure. The FOLLOWING op are presented in the form of a linked list: A non-negative integer denotes "enqueue me." -1 denotes either of the following: Dequeue the current root and append it to the result if the queue is not empty. Append -1 to the result if the queue is empty. The end result should be returned as a linked list. As an auxiliary data structure, use two stacks. It is not permitted to use a queue. C ++ code SNIPPET which solves the given Data Structures and Algorithm problem is given below: Node* makeAnswerList(Node root, Node last, int VALUE){ if (root == NULL) { root = new Node(value); last = root; } else { Node node = new Node(value); last->link = node; last = last->link; } return last;}int dequeue(stack &stk1, stack &stk2){ if (stk1.empty() && stk2.empty()) { return -1; } // If the second stack is not empty, popping and returning from it. if (stk2.empty() == false) { int value = stk2.top(); stk2.pop(); return value; } / Otherwise we pop each and every element from the first stack and push into the second stack. / while (stk1.empty() == false) { stk2.push(stk1.top()); stk1.pop(); } // Lastly, we pop and return the root of the second stack. int value = stk2.top(); stk2.pop(); return value;}Node implementingQueue(Node* op){ stack stk1, stk2; Node root = NULL; Node last = NULL; while (op != NULL) { if (op->val >= 0) { stk1.push(op->val); } else { last = makeAnswerList(root, last, dequeue(stk1, stk2)); if (!root) { root = last; } } op = op->link; } return root;} In this question, we use two stacks to implement the queue data structure. As soon as a non-negative integer is found, we add it into the first stack and when we get a -1 in the input list, we perform the dequeue operation using the following criteria: If the second stack is not empty, we return its TOPMOST value and pop it. If the second stack is empty, we pop all the elements of the first stack, push them into the second stack and at the end, we pop and return the topmost element of the second stack. This way, the FIFO (First In First Out) property of a queue is preserved and we get our required answer list.

5.

Write functional code for solving the problem given below:

Answer»

Return the result of a sequence of enqueue and dequeue actions without utilising a queue data structure. The FOLLOWING op are presented in the form of a linked list:

A non-negative integer denotes "enqueue me."
-1 denotes either of the following:
- Dequeue the current root and append it to the result if the queue is not empty.
- Append -1 to the result if the queue is empty.

The end result should be returned as a linked list. As an auxiliary data structure, use two stacks. It is not permitted to use a queue.

C ++ code SNIPPET which solves the given Data Structures and Algorithm problem is given below:

Node* makeAnswerList(Node *root, Node *last, int VALUE){ if (root == NULL) { root = new Node(value); last = root; } else { Node *node = new Node(value); last->link = node; last = last->link; } return last;}int dequeue(stack &stk1, stack &stk2){ if (stk1.empty() && stk2.empty()) { return -1; } // If the second stack is not empty, popping and returning from it. if (stk2.empty() == false) { int value = stk2.top(); stk2.pop(); return value; } /* Otherwise we pop each and every element from the first stack and push into the second stack. */ while (stk1.empty() == false) { stk2.push(stk1.top()); stk1.pop(); } // Lastly, we pop and return the root of the second stack. int value = stk2.top(); stk2.pop(); return value;}Node* implementingQueue(Node* op){ stack stk1, stk2; Node *root = NULL; Node *last = NULL; while (op != NULL) { if (op->val >= 0) { stk1.push(op->val); } else { last = makeAnswerList(root, last, dequeue(stk1, stk2)); if (!root) { root = last; } } op = op->link; } return root;}

In this question, we use two stacks to implement the queue data structure. As soon as a non-negative integer is found, we add it into the first stack and when we get a -1 in the input list, we perform the dequeue operation using the following criteria:

If the second stack is not empty, we return its TOPMOST value and pop it.
If the second stack is empty, we pop all the elements of the first stack, push them into the second stack and at the end, we pop and return the topmost element of the second stack.

This way, the FIFO (First In First Out) property of a queue is preserved and we get our required answer list.

Discussion

6.	Write functional code for solving the problem given below
Answer» "You have been GIVEN the string s (which consists of only uppercase English characters) and the integer k. You can replace any character in the string with ANOTHER uppercase English character. This operation can be performed at most k times. After executing the preceding procedures, RETURN the length of the longest substring containing the same letter." Sample input and output is shown below: Input: s = "AABABBA", k = 1 Output: 4 C ++ function which solves the given Data Structures and Algorithm problem is given below: int replaceCharacters(string s, int k) { int n = s.length(); int maxLength = 0, maxFreq = 0, l = 0; vector<int> freq(26); for(int r = 0; r < n; r ++){ int ascii = s[r] - 'A'; freq[ascii] ++; maxFreq = max(maxFreq, freq[ascii]); while(r - l + 1 - maxFreq > k){ freq[s[l] - 'A'] --; l ++; } maxLength = max(maxLength, r - l + 1); } return maxLength; } In this question, we use the sliding window technique along with two pointers "l" and "r" to get our answer. We keep moving the pointer "r" by one from left to right each iteration and update the frequency of all characters in the window starting from index l to r. If the difference of the subarray length l to r and maximum frequency among all the characters in the window of l to r is greater than the given VALUE k, we move l forward until the same condition does not hold (l's value is incremented hence subarray length, that is, the value of "r - l + 1" keeps decreasing). In the end, we update our answer variable with the value of the length of the subarray "r - l + 1" since we can guarantee that after performing at most k op, all characters in the subarray can be made the same.

6.

Write functional code for solving the problem given below

Answer»

"You have been GIVEN the string s (which consists of only uppercase English characters) and the integer k. You can replace any character in the string with ANOTHER uppercase English character. This operation can be performed at most k times. After executing the preceding procedures, RETURN the length of the longest substring containing the same letter."

Sample input and output is shown below:

Input: s = "AABABBA", k = 1
Output: 4

C ++ function which solves the given Data Structures and Algorithm problem is given below:

int replaceCharacters(string s, int k) { int n = s.length(); int maxLength = 0, maxFreq = 0, l = 0; vector<int> freq(26); for(int r = 0; r < n; r ++){ int ascii = s[r] - 'A'; freq[ascii] ++; maxFreq = max(maxFreq, freq[ascii]); while(r - l + 1 - maxFreq > k){ freq[s[l] - 'A'] --; l ++; } maxLength = max(maxLength, r - l + 1); } return maxLength; }

In this question, we use the sliding window technique along with two pointers "l" and "r" to get our answer. We keep moving the pointer "r" by one from left to right each iteration and update the frequency of all characters in the window starting from index l to r. If the difference of the subarray length l to r and maximum frequency among all the characters in the window of l to r is greater than the given VALUE k, we move l forward until the same condition does not hold (l's value is incremented hence subarray length, that is, the value of "r - l + 1" keeps decreasing). In the end, we update our answer variable with the value of the length of the subarray "r - l + 1" since we can guarantee that after performing at most k op, all characters in the subarray can be made the same.

Discussion

Explore topic-wise InterviewSolutions in .

In operating systems, define spooling.

What is Servlet Collaboration?

What is the difference between Swapping and Paging.

Write functional code for solving the problem given below: Detect whether or not a given linked list contains a cycle.

Write functional code for solving the problem given below:

Write functional code for solving the problem given below