Ciberspring Interview Questions and Answers

Round duration - 100 Minutes
Round difficulty - Medium

Q1. 
Change Start Node Problem Statement
You are provided with a singly linked list and an integer K. The objective is to make the Kth node from the end of the linked list the starting node of the linked list.
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Ans. 
Given a singly linked list and an integer K, rearrange the list such that the Kth node from the end becomes the starting node.
• Traverse the linked list to find the length and the Kth node from the end.

• Update the pointers to rearrange the list accordingly.

• Handle edge cases like K being equal to 1 or the length of the list.
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Q2. 
Valid Parentheses Problem Statement
Given a string 'STR' consisting solely of the characters “{”, “}”, “(”, “)”, “[” and “]”, determine if the parentheses are balanced.
Input:
The first line contains an...read more
Ans. 
Check if given strings containing parentheses are balanced or not.
• Use a stack to keep track of opening parentheses

• Iterate through the string and push opening parentheses onto the stack

• When a closing parentheses is encountered, pop from the stack and check if it matches the corresponding opening parentheses

• If stack is empty at the end and all parentheses are matched, the string is balanced
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Round duration - 120 Minutes
Round difficulty - Medium

Q1. 
Alien Dictionary Problem Statement
You are provided with a sorted dictionary (by lexical order) in an alien language. Your task is to determine the character order of the alien language from this dictiona...read more
Ans. 
Given a sorted alien dictionary in an array of strings, determine the character order of the alien language.
• Iterate through the dictionary to build a graph of character dependencies based on adjacent words.

• Perform a topological sort on the graph to determine the character order.

• Return the character array representing the order of characters in the alien language.
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Q2. 
Chocolate Distribution Problem
You are given an array/list CHOCOLATES of size 'N', where each element represents the number of chocolates in a packet. Your task is to distribute these chocolates among 'M'...read more
Ans. 
Distribute chocolates among students to minimize the difference between the largest and smallest number of chocolates.
• Sort the array of chocolates in ascending order.

• Iterate through the array and find the minimum difference between the elements by considering 'M' elements at a time.

• Return the minimum difference found as the result.
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Round duration - 120 Minutes
Round difficulty - Medium

Q1. 
Inplace Rotate Matrix 90 Degrees Anti-Clockwise
You are provided with a square matrix of non-negative integers of size 'N x N'. The task is to rotate this matrix by 90 degrees in an anti-clockwise directi...read more
Ans. 
Rotate a square matrix by 90 degrees anti-clockwise without using extra space.
• Iterate through each layer of the matrix from outer to inner layers

• Swap elements in groups of 4 to rotate them in place

• Handle odd-sized matrices separately by adjusting the loop boundaries
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Q2. 
Flip The Bits Problem Statement
Given a binary string S of length N where initially all characters are '1', perform exactly M operations, choosing from four specific operations, and determine how many dis...read more
Ans. 
Count the number of distinct final strings possible after performing a given number of operations on a binary string.
• Iterate through all possible combinations of operations to determine the final string after each operation.

• Use bitwise operations to efficiently flip the bits based on the chosen operation.

• Keep track of distinct final strings using a set data structure.

• Return the size of the set as the number of distinct...read more
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Round duration - 120 Minutes
Round difficulty - Medium

Q1. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. 
Find the Next Greater Element for each element in a list of integers.
• Iterate through the list of integers from right to left.

• Use a stack to keep track of elements for which the Next Greater Element is not yet found.

• Pop elements from the stack until a greater element is found or the stack is empty.

• Assign the Next Greater Element as the top element of the stack or -1 if the stack is empty.
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Round duration - 40 minutes
Round difficulty - Easy

Q1. 
Count Subsequences Problem Statement
Given an integer array ARR of size N, your task is to find the total number of subsequences in which all elements are equal.
Explanation:
A subsequence of an array i...read more
Ans. 
Count the total number of subsequences in which all elements are equal in an integer array.
• Iterate through the array and count the frequency of each element.

• Calculate the total number of subsequences for each element using the formula (frequency * (frequency + 1) / 2).

• Sum up the total number of subsequences for all elements and return the result modulo 10^9 + 7.
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