20+ FIS Interview Questions and Answers

Q1. Reverse Words in a String: Problem Statement

You are given a string of length N. Your task is to reverse the string word by word. The input may contain multiple spaces between words and may have leading or trai...read more

Q2. Rectangle Counting on an N x N Chessboard

Given a positive integer N, determine the number of possible rectangles that can be formed on an N x N chessboard, excluding squares.

Input:

The first line contains an ...read more

Q3. Rearrange Words in a Sentence

You are provided with a sentence 'TEXT'. Each word in the sentence is separated by a single space, and the sentence starts with a capital letter. Your task is to rearrange the word...read more

Q4. Sudoku Solver Problem Statement

You are provided with a 9x9 2D integer matrix MAT representing a Sudoku puzzle. The empty cells in the Sudoku are denoted by zeros, while the other cells contain integers from 1 ...read more

Q5. Sudoku Validity Problem Statement

You are provided with a 9 x 9 2D matrix MATRIX containing digits (1-9) and empty cells indicated by 0.

Your task is to determine if there exists a method to fill all empty cell...read more

Q6. Problem: Sort an Array of 0s, 1s, and 2s

Given an array/list ARR consisting of integers where each element is either 0, 1, or 2, your task is to sort this array in increasing order.

Input:

The input starts with...read more

Q7. Kth Largest Number Problem Statement

You are given a continuous stream of numbers, and the task is to determine the kth largest number at any moment during the stream.

Explanation:

A specialized data structure ...read more

Q8. Stack using Two Queues Problem Statement

Develop a Stack Data Structure to store integer values using two Queues internally.

Your stack implementation should provide these public functions:

Explanation:

1. Cons...read more

Q9. Fastest Horse Problem Statement

Given ‘N’ horses running in separate lanes, each horse's finish time is provided in an array. You are tasked to process 'Q' queries. For each query, determine the time taken by t...read more

Q10. LRU Cache Problem Statement

Design and implement a data structure for the Least Recently Used (LRU) Cache to efficiently support the following operations:

1. get(key): Retrieve the value of the key if it exists i...read more

Q11. Next Greater Number Problem Statement

Given a string S which represents a number, determine the smallest number strictly greater than the original number composed of the same digits. Each digit's frequency from...read more

Q12. Merge Two Sorted Linked Lists Problem Statement

You are provided with two sorted linked lists. Your task is to merge them into a single sorted linked list and return the head of the combined linked list.

Input:...read more

Q13. Intersection of Linked List Problem

You are provided with two singly linked lists containing integers, where both lists converge at some node belonging to a third linked list.

Your task is to determine the data...read more

Q14. Shortest Path in a Binary Matrix Problem Statement

Given a binary matrix of size N * M where each element is either 0 or 1, find the shortest path from a source cell to a destination cell, consisting only of 1s...read more

Q15. Distance Between Two Nodes in a Binary Tree

Given a binary tree and the values of two distinct nodes, determine the distance between these two nodes in the tree. The distance is defined as the minimum number of...read more

Q16. Longest Palindromic Substring Problem Statement

You are provided with a string STR of length N. The goal is to identify the longest palindromic substring within this string. In cases where multiple palindromic ...read more

Q17. Most Frequent Non-Banned Word Problem Statement

Given a paragraph consisting of letters in both lowercase and uppercase, spaces, and punctuation, along with a list of banned words, your task is to find the most...read more

Q18. Count Subarrays with Given XOR Problem Statement

You are given an array of integers ARR and an integer X. Your task is to determine the number of subarrays of ARR whose bitwise XOR is equal to X.

Example:

Input...read more

Q19. Populating Next Right Pointers in Each Node

Given a complete binary tree with 'N' nodes, your task is to determine the 'next' node immediately to the right in level order for each node in the given tree.

Input:...read more

Q20. Pair Sum Problem Statement

You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.

Note:

Each pa...read more