400+ Pioneer Valves & Flow Control Interview Questions and Answers

Q1. Crazy Numbers Pattern Challenge

Ninja enjoys arranging numbers in a sequence. He plans to arrange them in 'N' rows such that:

• The first row contains 1 number.
• The second row contains 2 numbers.
• The third row c...read more

Q2. String Compression Problem Statement

Ninja needs to perform basic string compression. For any character that repeats consecutively more than once, replace the repeated sequence with the character followed by th...read more

Q3. Ninja and the New Year Guests Problem

Ninja has organized a new year party and wants to verify if the guests are programmers by challenging them with a coding task. As an invited programmer, you're tasked to so...read more

Q5. Swap Kth Elements in an Array

Given an array ARR of size N, perform the operation to swap the Kth element from the beginning with the Kth element from the end of the array.

Example:

Input:

N = 5, K = 2
ARR = [1,...read more

Q6. Maximum Subarray Sum Problem Statement

Given an array arr of length N consisting of integers, find the sum of the subarray (including empty subarray) with the maximum sum among all subarrays.

Explanation:

A sub...read more

Q7. Maximum Meetings Problem Statement

Given the schedule of N meetings with their start time Start[i] and end time End[i], you need to determine which meetings can be organized in a single meeting room such that t...read more

Q8. Fibonacci Membership Check

Given an integer N, determine if it is a member of the Fibonacci series. Return true if the number is a member of the Fibonacci series, otherwise return false.

Fibonacci Series Defini...read more

Q9. Ways To Make Coin Change

Given an infinite supply of coins of varying denominations, determine the total number of ways to make change for a specified value using these coins. If it's not possible to make the c...read more

Q10. Longest Increasing Subsequence Problem Statement

Given an array of integers with 'N' elements, determine the length of the longest subsequence where each element is greater than the previous element. This subse...read more

Q11. Coin Game Winner Problem Statement

Two players 'X' and 'Y' are participating in a coin game. Starting with 'N' coins, players alternate turns, with 'X' starting first. On each turn, a player has three choices: ...read more

Q12. Next Permutation Problem Statement

You are given a permutation of 'N' integers. A sequence of 'N' integers is considered a permutation if it includes all integers from 1 to 'N' exactly once. Your task is to rea...read more

Q13. 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

Q14. Count Pairs with Difference K

Given an array of integers and an integer K, determine and print the count of all pairs in the array that have an absolute difference of K.

Input:

The first line of the input conta...read more

Q15. Find Duplicates in an Array

Given an array ARR of size 'N', where each integer is in the range from 0 to N - 1, identify all elements that appear more than once.

Return the duplicate elements in any order. If n...read more

Q16. Count Ways To Reach The N-th Stair Problem Statement

You are given a number of stairs, N. Starting at the 0th stair, you need to reach the Nth stair. Each time you can either climb one step or two steps. You ha...read more

Q17. Trapping Rain Water Problem Statement

You are given a long type array/list ARR of size N, representing an elevation map. The value ARR[i] denotes the elevation of the ith bar. Your task is to determine the tota...read more

Q18. Digits Decoding Problem Statement

A few days back, Ninja encountered a string containing characters from ‘A’ to ‘Z’ which indicated a secret message. For security purposes, he encoded each character of the stri...read more

Q19. Closest Perfect Square Problem Statement

Given a positive integer 'N', determine the perfect square number closest to 'N' and the number of steps required to reach that perfect square.

Example:

Input:

N = 21

Ou...read more

Q20. Find the Longest Palindromic Substring

Given a string ‘S’ composed of lowercase English letters, your task is to identify the longest palindromic substring within ‘S’.

If there are multiple longest palindromic ...read more

Q21. Nth Prime Number Problem Statement

Find the Nth prime number given a number N.

Explanation:

A prime number is greater than 1 and is not the product of two smaller natural numbers. A prime number has exactly two...read more

Q22. Missing Number Statement

Given an array ARR of integers with size N, where all elements appear an even number of times except for one element which appears an odd number of times, identify the element that appe...read more

Q23. Nearest Numbers with the Same Number of Set Bits

Given a positive integer n, your task is to determine the next smallest integer and the previous largest integer that have the same number of '1' bits in their b...read more

Q24. Complete String Problem Statement

Given an array of strings A of size N, determine the longest complete string. A string is deemed complete if every prefix of the string also appears in the array. If multiple s...read more

Q25. Palindrome String Validation

Determine if a given string 'S' is a palindrome, considering only alphanumeric characters and ignoring spaces and symbols.

Note:

The string 'S' should be evaluated in a case-insensi...read more

Q26. Equilibrium Index Problem Statement

Given an array Arr consisting of N integers, your task is to find the equilibrium index of the array.

An index is considered as an equilibrium index if the sum of elements of...read more

Q27. 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 integer...read more

Q28. Secret Message Decoding Problem

Ninja encountered an encoded secret message where each character from 'A' to 'Z' is mapped to a numeric value (A = 1, B = 2, ..., Z = 26). Given a numeric sequence (SEQ) derived ...read more

Q29. 0/1 Knapsack Problem Statement

A thief is planning to rob a store and can carry a maximum weight 'W' in their knapsack. The store contains 'N' items, each with a known weight and value. Given these constraints,...read more

Q30. K - Sum Path In A Binary Tree

Given a binary tree where each node contains an integer value, and a value 'K', your task is to find all the paths in the binary tree such that the sum of the node values in each p...read more

Q31. Convert Sentence Problem Statement

Convert a given string 'S' into its equivalent representation based on a mobile numeric keypad sequence. Using the keypad layout shown in the reference, output the sequence of...read more

Q32. Prime Numbers Identification

Given a positive integer N, your task is to identify all prime numbers less than or equal to N.

Explanation:

A prime number is a natural number greater than 1 that has no positive d...read more

Q33. Subsequences of String Problem Statement

You are provided with a string 'STR' that consists of lowercase English letters ranging from 'a' to 'z'. Your task is to determine all non-empty possible subsequences of...read more

Q34. K Subsets with Equal Sum Problem Statement

Determine whether it is possible to partition an array ARR into K subsets, each having an equal sum.

Example:

Input:

ARR = [3, 5, 2, 4, 4], K = 2

Output:

true

Explanat...read more

Q35. Count Derangements

Determine the number of derangements possible for a set of 'N' elements. A derangement is a permutation where no element appears in its original position.

Input:

An integer 'T' representing t...read more

Q36. Rearrange Array: Move Negative Numbers to the Beginning

Given an array ARR consisting of N integers, rearrange the elements such that all negative numbers are located before all positive numbers. The order of e...read more

Q37. Common Elements Problem Statement

Identify and output the common strings present in both given arrays of lowercase alphabets for each test case.

Input:

The first line contains an integer 'T' representing the nu...read more

Q38. Character Counting Challenge

Create a program that counts and prints the total number of specific character types from user input. Specifically, you need to count lowercase English alphabets, numeric digits (0-...read more

Q39. N-th Term Of Geometric Progression

Find the N-th term of a Geometric Progression (GP) series given the first term A, the common ratio R, and the term position N.

Explanation:

The general form of a GP series is ...read more

Q40. K Sum Subset Problem Statement

Given an array arr of size 'N' and an integer 'K', determine the maximum subset sum of the array that does not exceed 'K'.

Example:

Input:

arr = [1, 3, 5, 9], K = 16

Output:

15

Ex...read more

Q41. Trailing Zeros in Factorial Problem

Find the number of trailing zeroes in the factorial of a given number N.

Input:

The first line contains an integer T representing the number of test cases.
Each of the followi...read more

Q42. Minimum Number of Platforms Needed Problem Statement

You are given the arrival and departure times of N trains at a railway station for a particular day. Your task is to determine the minimum number of platform...read more

Q43. Letter Combinations of a Phone Number Problem Statement

You are given a string S containing digits from 2 to 9 inclusive. Your task is to find all possible letter combinations that the number could represent, b...read more

Q44. 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

Q45. Find All Pairs Adding Up to Target

Given an array of integers ARR of length N and an integer Target, your task is to return all pairs of elements such that they add up to the Target.

Input:

The first line conta...read more

Q46. Find the Second Largest Element

Given an array or list of integers 'ARR', identify the second largest element in 'ARR'.

If a second largest element does not exist, return -1.

Example:

Input:

ARR = [2, 4, 5, 6, ...read more

Q47. Validate BST Problem Statement

Given a binary tree with N nodes, determine whether the tree is a Binary Search Tree (BST). If it is a BST, return true; otherwise, return false.

A binary search tree (BST) is a b...read more

Q48. Sort a "K" Sorted Doubly Linked List Problem Statement

You are given a doubly linked list with 'N' nodes, where each node can deviate at most 'K' positions from its actual position in the sorted list. Your task...read more

Q49. First Non-Repeating Character Problem Statement

You are given a string consisting of English alphabet characters. Your task is to identify and return the first character in the string that does not repeat. If e...read more

Q50. Partition to K Equal Sum Subsets Problem

Given an array of integers and a positive integer 'K', determine if it is possible to divide the array into 'K' non-empty subsets such that the sum of elements in each s...read more

Q51. Sort a "K" Sorted Doubly Linked List

Given a doubly-linked list with N nodes, where each node’s position deviates at most K positions from its position in the sorted list, your task is to sort this given doubly...read more

Q52. Counting Derangements Problem

A derangement is a permutation of 'N' elements, where no element appears in its original position. For instance, a derangement of {0, 1, 2, 3} is {2, 3, 1, 0} because each element ...read more

Q53. Reverse Alternate K Nodes Problem Statement

You are given a singly linked list of integers along with a positive integer 'K'. The task is to modify the linked list by reversing every alternate 'K' nodes of the ...read more

Q55. Convert First Letter to Upper Case

Given a string STR, transform the first letter of each word in the string to uppercase.

Example:

Input:

STR = "I am a student of the third year"

Output:

"I Am A Student Of The...read more

Q56. Print All Paths Problem Statement

In this problem, you are provided with a graph consisting of 'N' nodes and 'M' unidirectional edges. Additionally, two integers 'S' and 'D' are given, representing the source a...read more

Q57. Maximum Path Sum Between Two Leaves

Given a non-empty binary tree where each node has a non-negative integer value, determine the maximum possible sum of the path between any two leaves of the given tree.

Expla...read more

Q58. Stock Trading Maximum Profit Problem

Given the stock prices for 'N' days, your goal is to determine the maximum profit that can be achieved. You can buy and sell the stocks any number of times but can only hold...read more

Q59. Word Break Problem Statement

You are given a list of N strings called A. Your task is to determine whether you can form a given target string by combining one or more strings from A.

The strings from A can be u...read more

Q60. Rotational Equivalence of Strings Problem Statement

Given two strings 'P' and 'Q' of equal length, determine if string 'P' can be transformed into string 'Q' by cyclically rotating it to the right any number of...read more

Q61. Merge k Sorted Linked Lists

You are provided with 'K' sorted linked lists, each sorted in increasing order. Your task is to merge all these lists into one single sorted linked list and return the head of the re...read more

Q62. Number of Islands Problem Statement

You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in this ma...read more

Q63. Zigzag Binary Tree Traversal Problem

Given a binary tree, compute the zigzag level order traversal of the node values in the tree. The zigzag traversal requires traversing levels from left to right, then right ...read more

Q64. Maximum Meetings Selection

You are tasked with scheduling meetings in a single meeting room. Given N meetings, each with a start time Start[i] and end time End[i], determine the maximum number of meetings that ...read more

Q65. Remove String from Linked List Problem

You are provided with a singly linked list where each node contains a single character, along with a string 'STR'. Your task is to remove all occurrences of the string 'ST...read more

Q66. Most Frequent Word Problem Statement

You are given two strings 'A' and 'B' composed of words separated by spaces. Your task is to determine the most frequent and lexicographically smallest word in string 'A' th...read more

Q67. Guess The Hidden Number Problem Statement

You are given an integer N and there is a hidden number within the range [0, N] that you must guess. You have access to a function higherLower(k) which helps in guessin...read more

Q68. Detect and Remove Loop in Linked List

For a given singly linked list, identify if a loop exists and remove it, adjusting the linked list in place. Return the modified linked list.

Expected Complexity:

Aim for a...read more

Q69. Trapping Rainwater Problem Statement

You are given an array ARR of long type, which represents an elevation map where ARR[i] denotes the elevation of the ith bar. Calculate the total amount of rainwater that ca...read more

Q70. String Rotation Problem Statement

You are given a string named str and an integer D. Your task is to perform both left (anticlockwise) and right (clockwise) rotations on the given string by D units, starting fr...read more

Q71. Merge Sort Linked List Problem Statement

You are given a singly linked list of integers. Your task is to sort the linked list using the merge sort algorithm.

Explanation:

Merge Sort is a divide and conquer algo...read more

Q72. Reverse Linked List Problem Statement

Given a Singly Linked List of integers, your task is to reverse the Linked List by altering the links between the nodes.

Input:

The first line of input is an integer T, rep...read more

Q73. Minimum Steps for a Knight to Reach Target

Given a square chessboard of size N x N, you need to determine the minimum number of steps a Knight takes to reach a target position from its starting position.

Input:...read more

Q74. Count Palindrome Words in a String

Given a string 'S' consisting of words, your task is to determine the number of palindrome words within 'S'. A word is considered a palindrome if it reads the same backward as...read more

Q75. Preorder Traversal Problem Statement

You are provided with the root node of a binary tree comprising N nodes. Your objective is to output its preorder traversal. Preorder traversal of a binary tree is performed...read more

Q76. Check If Binary Representation of a Number is Palindrome

Given an integer N, determine if its binary representation is a palindrome.

Input:

The first line contains a single integer ‘T’ representing the number o...read more

Q77. Duplicate Subtrees Problem Statement

Given a binary tree, return the root values of all duplicate subtrees. Two subtrees are considered duplicate if they have the same structure with identical node values. For ...read more

Q78. Make Unique Array Challenge

Your task is to determine the minimum number of elements that need to be removed from an array 'ARR' of size 'N' such that all the remaining elements are distinct. In simpler terms, ...read more

Q79. Distribute N Candies Among K People

Explanation: Sanyam wishes to distribute 'N' candies among 'K' friends. The friends are arranged based on Sanyam's order of likeness. He initially distributes candies such th...read more

Q80. Median of Two Sorted Arrays

Given two sorted arrays A and B of sizes N and M, find the median of the merged array formed by combining arrays A and B. If the total number of elements, N + M, is even, the median ...read more

Q81. Sort 0 and 1 Problem Statement

Given an integer array ARR of size N containing only integers 0 and 1, implement a function to sort this array. The solution should scan the array only once without using any addi...read more

Q82. Spiral Order Traversal of a Binary Tree

Given a binary tree with N nodes, your task is to output the Spiral Order traversal of the binary tree.

Input:

The input consists of a single line containing elements of ...read more

Q83. Code Optimization Problem

Ninja encountered an issue with a practice problem where certain test cases could not be passed due to high time complexity. You are provided with a snippet of pseudocode, and your tas...read more

Q84. Binary Palindrome Check

Given an integer N, determine whether its binary representation is a palindrome.

Input:

The first line contains an integer 'T' representing the number of test cases. 
The next 'T' lines e...read more

Q85. Character Formation Check

Determine if the second string STR2 can be constructed using characters from the first string STR1. Both strings may include any characters.

Input:

The first line contains an integer T...read more

Q86. Count Pairs with Given Sum

Given an integer array/list arr and an integer 'Sum', determine the total number of unique pairs in the array whose elements sum up to the given 'Sum'.

Input:

The first line contains ...read more

Q87. Jumping Game Problem Statement

In this problem, you have ‘n’ carrots lined up and denoted by numbers 1 through ‘n’. There are ‘k’ rabbits, and each rabbit can jump to carrots that are multiples of its unique ju...read more

Q88. Reverse Stack with Recursion

Reverse a given stack of integers using recursion. You must accomplish this without utilizing extra space beyond the internal stack space used by recursion. Additionally, you must r...read more

Q89. String Transformation Problem

Given a string (STR) of length N, you are tasked to create a new string through the following method:

Select the smallest character from the first K characters of STR, remove it fr...read more

Q90. Segregate Odd-Even Problem Statement

In a wedding ceremony at NinjaLand, attendees are divided into two groups: bride’s side and groom’s side. Attendees from the bride’s side hold odd numbers, while those from ...read more

Q92. Smallest Window Problem Statement

Given two strings S and X containing random characters, the task is to find the smallest substring in S which contains all the characters present in X.

Input:

The first line co...read more

Q94. Count Derangements Problem Statement

You are tasked with finding the total number of derangements for a given set of elements. Specifically, for an integer N, determine how many ways there are to permute a set ...read more

Q97. Factorial Calculation Problem Statement

Develop a program to compute the factorial of a given integer 'n'.

The factorial of a non-negative integer 'n', denoted as n!, is the product of all positive integers les...read more

Q99. DFS Traversal Problem Statement

Given an undirected and disconnected graph G(V, E), where V is the number of vertices and E is the number of edges, the connections between vertices are provided in the 'GRAPH' m...read more