200+ Evaluationz India Interview Questions and Answers

Q1. Fish Eater

There is a river which flows in one direction. One day, the river has 'N' number of fishes. You are given an array 'FISHES' of integers representing the size of 'N' fishes. The fishes are present in t...read more

Q2. Longest Increasing Subsequence

For a given array with N elements, you need to find the length of the longest subsequence from the array such that all the elements of the subsequence are sorted in strictly increa...read more

Q3. Kth Smallest and Largest Element of Array

You are given an array ‘Arr’ consisting of ‘N’ distinct integers and a positive integer ‘K’. Find out Kth smallest and Kth largest element of the array. It is guaranteed...read more

Q4. First Missing Positive

You are given an array 'ARR' of integers of length N. Your task is to find the first missing positive integer in linear time and constant space. In other words, find the lowest positive in...read more

Q5. Container With Most Water

Given a sequence of ‘N’ space-separated non-negative integers A[1],A[2],A[3],......A[i]…...A[n]. Where each number of the sequence represents the height of the line drawn at point 'i'. ...read more

Q6. Pair Sum

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

Note:

Each pair shou...read more

Q7. Frequency In A Sorted Array

You are given a sorted array 'ARR' and a number 'X'. Your task is to count the number of occurrences of 'X' in 'ARR'.

Note :

1. If 'X' is not found in the array, return 0. 2. The give...read more

Q8. Maximum Of All Subarrays Of Size k

You are given an array “A” of N integers. Your task is to find the maximum element in all K sized contiguous subarrays from left to right.

For Example:

If A = [3, 2, 3], and K ...read more

Q9. Flip Bits

You are given an array of integers ARR[] of size N consisting of zeros and ones. You have to select a subset and flip bits of that subset. You have to return the count of maximum one’s that you can obt...read more

Q10. Matrix Median

You have been given a matrix of ‘N’ rows and ‘M’ columns filled up with integers where every row is sorted in non-decreasing order. Your task is to find the overall median of the matrix i.e if all ...read more

Q11. Count triplets in a sorted doubly linked list whose sum is equal to a given value x

You have been given an integer ‘X’ and a non-decreasing sorted doubly linked list with distinct nodes.

Your task is to return t...read more

Q12. The Celebrity Problem

There are ‘N’ people at a party. Each person has been assigned a unique id between 0 to 'N' - 1(both inclusive). A celebrity is a person who is known to everyone but does not know anyone at...read more

Q13. Minimum Travel Cost

Ninjaland is a country having 'N' states numbered from 1 to 'N'. These 'N' states are connected by 'M' bidirectional roads. Each road connects to different states and has some cost to travel ...read more

Q14. Valid Sudoku

You have been given a 9 X 9 2D matrix 'MATRIX' with some cells filled with digits(1 - 9), and some empty cells (denoted by 0).

You need to find whether there exists a way to fill all the empty cells...read more

Q15. Clone Linked List with Random Pointer

Given a linked list having two pointers in each node. The first one points to the next node of the list, however, the other pointer is random and can point to any node of th...read more

Q16. Saving Money

Ninja likes to travel a lot, but at the same time, he wants to save as much money as possible. There are ‘N’ Stations connected by ‘M’ Trains. Each train that he boards starts from station ‘A’ and r...read more

Q17. Sort Linked List

You are given a Singly Linked List of integers which is sorted based on absolute value.

You have to sort the Linked List based on actual values.

The absolute value of a real number x, denoted |x...read more

Q18. Product Of Array Except Self

You have been given an integer array/list (ARR) of size N. You have to return an array/list PRODUCT such that PRODUCT[i] is equal to the product of all the elements of ARR except ARR...read more

Q19. First Repeated Character

You are given a string 'STR' of lowercase English alphabets. You need to find the repeated character present first in the string.

Example:

If the string is: “abccba”, then the first repe...read more

Q20. Subtree of Another Tree

Given two binary trees T and S, check whether tree S has exactly the same structure and node values with a subtree of T, i.e., check if tree S is a subtree of the tree T.

A subtree of a t...read more

Q21. Count triplets in a sorted doubly linked list whose sum is equal to a given value x

You are given a sorted doubly linked list of distinct nodes that means no two nodes present in the list have the same data. You...read more

Q22. Count Inversions

For a given integer array/list 'ARR' of size 'N', find the total number of 'Inversions' that may exist.

An inversion is defined for a pair of integers in the array/list when the following two co...read more

Q23. Total unique paths

You are present at point ‘A’ which is the top-left cell of an M X N matrix, your destination is point ‘B’, which is the bottom-right cell of the same matrix. Your task is to find the total num...read more

Q24. Given a string with no separator, find the missing number in the string

You had a sequence of consecutive nonnegative integers. You appended all integers at the end of each other to form a string ‘S’ without any...read more

Q25. Subsequences of String

You are given a string 'STR' containing lowercase English letters from a to z inclusive. Your task is to find all non-empty possible subsequences of 'STR'.

A Subsequence of a string is the...read more

Q26. Simplify the Directory

You are given a path to a file/directory in Unix-style of length N, In a Unix-style file system, a dot(.) refers to the current directory. A double dot(..) refers to the previous directory...read more

Q27. Valid String

You have been given a string 'S' containing only three types of characters, i.e. '(', ')' and '*'.

A Valid String is defined as follows:

1. Any left parenthesis '(' must have a corresponding right p...read more

Q28. Flip Bit to Win

Ninjas are often known for their stealth execution and accuracy to get the job done right. While honing their art of moving through dense forests stealthily, they need the maximum number of conti...read more

Q29. Chocolate Problem

Given an array/list of integer numbers 'CHOCOLATES' of size 'N', where each value of the array/list represents the number of chocolates in the packet. There are ‘M’ number of students and the t...read more

Q30. Row with Maximum 1's

You have been given a non-empty grid ‘MAT’ with 'N' rows and 'M' columns consisting of only 0s and 1s. All the rows are sorted in ascending order.

Your task is to find the index of the row t...read more

Q31. NINJA'S JUMP

Ninja is assigned a task to reach the last stone by his master. These stones are numbered with some value and in the form of an array. He is allowed to jump either odd-numbered jumps or even-numbere...read more

Q32. Anagram Pairs

Pre-requisites: Anagrams are defined as words or names that can be formed by rearranging letters of another word. Such as "spar" can be formed by rearranging letters of "rasp". Hence, "spar" and "r...read more

Q33. Word Break

You are given a list of “N” strings A. Your task is to check whether you can form a given target string using a combination of one or more strings of A.

Note :

You can use any string of A multiple tim...read more

Q34. Longest Sub-string with at most K Distinct Characters

You are given string S of length N, and an integer K. Your task is to find the length of the longest substring that contains at most K distinct characters.

I...read more

Q35. Minimum Cost to cross Grid

You are given a 2 - D grid having ‘N’ rows and ‘M’ columns. Each cell of the grid has an integer value written on it which denotes the cost it takes to pass through that cell. You are ...read more

Q36. Distinct palindromic sub-strings of a string

You have been given a string STR. Your task is to find the total number of palindromic substrings of STR.

Example :

If the input string is "abbc", then all the possib...read more

Q37. Reverse Linked List

You are given a Singly Linked List of integers. You need to reverse the Linked List by changing the links between nodes.

Input Format :

The first line of input contains a single integer T, re...read more

Q38. Sorted Subsequence of Size 3

You are given an array consisting of N elements and you need to find a subsequence consisting of three elements such that the elements, in the subsequence, are in strictly increasing...read more

Q39. Count Ways To Reach The N-th Stairs

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

Q40. Bottom View Of Binary Tree

Given a binary tree, print its bottom view from left to right. Assume, the left and the right child make a 45-degree angle with the parent.

A binary tree is a tree in which each parent...read more

Q41. Knight Probability in Chessboard

You are given an N x N chessboard and a knight. On a chessboard, the knight can supposedly move in 8 different positions from its original position i.e. if the knight is original...read more

Q42. Reachable Nodes

You are given a graph with ‘N’ nodes and ‘M’ unidirectional edges. Your task is to find the number of nodes reachable from node ‘i’, where 0 <= ‘i’ <= ‘N’ - 1.

Note: A node ‘u’ is said to be reac...read more

Q43. LRU Cache Implementation

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

1. get(key) - Return the value of the key if the key exists in the cache, o...read more

Q44. Find Number of Islands

You are given a 2-dimensional array/list having N rows and M columns, which is filled with ones(1) and zeroes(0). 1 signifies land, and 0 signifies water.

A cell is said to be connected to...read more

Q45. Circular Array Loop

You are given a circular array 'ARR' of size 'N', consisting of positive and negative integers. For each index 'i', if ARR[i] is positive then move ARR[i] steps in clockwise direction else mo...read more

Q46. Favourite Operation

Ninja has recently studied operators ‘AND’ and ‘XOR’. His teacher gave him an assignment related to the two operators but Ninja is taking a lot of time to compute it and he is afraid he would...read more

Q47. Find Duplicate in Array

You are given an array of integers 'ARR' containing N elements. Each integer is in the range [1, N-1], with exactly one element repeated in the array.

Your task is to find the duplicate e...read more

Q48. Palindrome Linked List

You are given a singly Linked List of integers. Your task is to return true if the given singly linked list is a palindrome otherwise returns false.

For example:

The given linked list is 1...read more

Q49. Convert a binary tree to its sum tree

Given a binary tree of integers, you are supposed to modify the given binary tree to a sum tree where each node value is replaced by the sum of the values of both left and r...read more

Q50. Longest Decreasing Subsequence

You are given an array/list ARR consisting of N integers. Your task is to find the length of the longest decreasing subsequence.

A subsequence is a sequence of numbers obtained by ...read more

Q51. Maximum Product Subarray

You are given an array “arr'' of integers. Your task is to find the contiguous subarray within the array which has the largest product of its elements. You have to report this maximum pr...read more

Q52. Check If Linked List Is Palindrome

You are given a Singly Linked List of integers. You have to find if the given linked list is palindrome or not.

A List is a palindrome if it reads the same from the left to the...read more

Q53. Sort An Array According To The Count Of Set Bits

You are given an array consisting of N positive integers, and your task is to sort the array in decreasing order of count of set bits in the binary representation...read more

Q54. Squares of a Sorted Array

You are given an array/list ‘ARR’ of ‘N’ integers. You have to generate an array/list containing squares of each number in ‘ARR’, sorted in increasing order.

For example :

Input: ‘ARR’ ...read more

Q55. Return in Row wave form

You are given a 2D array with dimensions ‘N*M’. You need to read the array elements row-wise and return a linear array that stores the elements like a wave i.e the 1st-row elements are s...read more

Q56. Flatten BST To A Sorted List

You have been given a Binary Search Tree (BST). Your task is to flatten the given BST to a sorted list. More formally, you have to make a right-skewed BST from the given BST, i.e., t...read more

Q57. Amazing Strings

Given 3 Strings, check whether the 3rd string contains all the characters of string 1 and 2 in any order. If all the characters are present, print "YES" otherwise print "NO".

There should not be ...read more

Q58. Square root (decimal)

You have been given two integers 'N' and 'D', Your task is to find the square root of the number 'N' with precision up to 'D' decimal places i.e. the difference between your answer and the ...read more

Q59. Snake and Ladder

Given a snake and ladder board, find the minimum number of dice throws required to reach the destination or last cell from source or 1st cell. Basically, the player has total control over the ou...read more

Q60. Two Sum in a BST

You have been given a Binary Search Tree and a target value. You need to find out whether there exists a pair of node values in the BST, such that their sum is equal to the target value.

A binar...read more

Q61. Rotting Oranges

You have been given a grid containing some oranges. Each cell of this grid has one of the three integers values:

Value 0 - representing an empty cell.

Value 1 - representing a fresh orange.

...read more

Q62. Search in a row wise and column wise sorted matrix

You are given an N * N matrix of integers where each row and each column is sorted in increasing order. You are given a target integer 'X'. Find the position of...read more

Q63. Dice Throws

You are given D dice, each having F faces numbered 1 to F, both inclusive. The task is to find the possible number of ways to roll the dice together such that the sum of face-up numbers equal the giv...read more

Q64. Critical Connection

You are given a network with ‘N’ system nodes [0 to N - 1] and ‘M’ connection. Your task is to find out all critical connections in a given network.

Note: A connection between node ‘u’ and ‘v...read more

Q65. Count Distinct Element in Every K Size Window

You are given an array ‘ARR’ of size ‘N’ and an integer ‘K’. Your task is to find the total number of distinct elements present in every ‘K’ sized window of the arr...read more

Q66. Unique Element In Sorted Array

Nobita wants to impress Shizuka by guessing her lucky number.

Shizuka gave Nobita a sorted list of ‘N’ numbers such that every number occurred twice in the list except Shizuka’s lu...read more

Q67. Longest Palindromic Substring

You are given a string (STR) of length N.

Your task is to find the longest palindromic substring. If there is more than one palindromic substring with the maximum length, return the...read more

Q68. Position of Right Most Set Bit

You are given a number N. You need to return the position of the rightmost set bit.

For example:

If the given number is 10 with the binary representation: 1010 The rightmost set bi...read more

Q69. Row Of A Matrix With Maximum Ones

You are given a 2D matrix (containing either ‘0’ or ‘1’) of size N x M, where each row is in sorted order. Find the 0-based index of the first row that has the maximum number of...read more

Q70. Find pair with maximum GCD in an array

You are given an array of positive integers. Find the GCD(Greatest Common Divisor) of a pair of elements such that it is maximum among all possible pairs. GCD(a, b) is the ...read more

Q71. Largest rectangle in a histogram

You have been given an array/list 'HEIGHTS' of length ‘N. 'HEIGHTS' represents the histogram and each element of 'HEIGHTS' represents the height of the histogram bar. Consider th...read more

Q72. Snake and Ladder

You have been given a Snake and Ladder Board with 'N' rows and 'N' columns with the numbers written from 1 to (N*N) starting from the bottom left of the board, and alternating direction each row...read more

Q73. Two Sum

You are 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 Target.

Note:

We cannot use the element at a given inde...read more

Q74. Merge Two Sorted Linked Lists

You are given two sorted linked lists. You have to merge them to produce a combined sorted linked list. You need to return the head of the final linked list.

Note:

The given linked ...read more

Q75. Sorted Linked List to Balanced BST

You have been given a singly linked list in which nodes are present in increasing order. Your task is to construct a Balanced Binary Search Tree with the same data elements as ...read more

Q76. Majority element

You have been given an array/list 'ARR' consisting of 'N' integers. Your task is to find the majority element in the array. If there is no majority element present, print -1.

Note:

A majority el...read more

Q77. Bridges in a Graph

Given an undirected graph of V vertices and E edges. Your task is to find all the bridges in the given undirected graph. A bridge in any graph is defined as an edge which, when removed, makes...read more

Q78. Prerequisite Task

You are given a positive integer ‘N’ denoting the number of tasks you need to finish. You can directly start performing any task, but some tasks have some prerequisites, i.e. to perform some ta...read more

Q79. Convert Bst To The Greater Sum Tree

You have been given a Binary Search Tree of integers. You are supposed to convert it to a greater sum tree such that the value of every node in the given BST is replaced with ...read more

Q80. Maximum Sum of nodes in a binary tree such that no two nodes are adjacent

You have been given a binary tree with an integer value associated to each node. You are supposed to choose a subset of these nodes such ...read more

Q81. Subarray with equal occurrences

You have been given an array/list ARR of length N consisting of 0s and 1s only. Your task is to find the number of subarrays(non-empty) in which the number of 0s and 1s are equal....read more

Q82. Time to Burn Tree

You have been given a binary tree of 'N' unique nodes and a Start node from where the tree will start to burn. Given that the Start node will always exist in the tree, your task is to print the...read more

Q83. Distance between nodes of a binary tree

Given a binary tree and the value of two nodes, find the distance between the given two nodes of the Binary Tree.

Distance between two nodes is defined as the minimum numb...read more

Q84. Longest Consecutive Sequence

You are given an unsorted array/list 'ARR' of 'N' integers. Your task is to return the length of the longest consecutive sequence.

The consecutive sequence is in the form ['NUM', 'NU...read more

Q85. Data Structure Supporting Insert Delete And GetRandom

Design and implement a data structure which supports the following operations:

insert(X): Inserts an element X in the data structure and returns true if the ...read more

Q86. Number of Islands

You have been given a non-empty grid consisting of only 0s and 1s. You have to find the number of islands in the given grid.

An island is a group of 1s (representing land) connected horizontall...read more

Q87. Transform BST to greater sum tree

You have been given a Binary Search Tree of integers. You are supposed to convert it to a greater sum tree such that the value of every node in the given BST is replaced with th...read more

Q88. Maximum Path Sum in the matrix

You have been given an N*M matrix filled with integer numbers, find the maximum sum that can be obtained from a path starting from any cell in the first row to any cell in the last...read more

Q89. Missing Number

You are given an array/list ‘BINARYNUMS’ that consists of ‘N’ distinct strings which represent all integers from 0 to N in binary representation except one integer. This integer between 0 to ‘N’ w...read more

Q90. Spiral Order Traversal of a Binary Tree

You have been given a binary tree of 'N' nodes. Print the Spiral Order traversal of this binary tree.

For example

For the given binary tree [1, 2, 3, -1, -1, 4, 5, -1, -1,...read more

Q91. Power Set

You are given a sorted array of 'N' integers. You have to generate the power set for this array where each subset of this power set is individually sorted.

A set is a well-defined collection of distinc...read more

Q92. Check whether second string can be formed from characters of first string

You are given two strings STR1 and STR2. You need to check whether STR2 can be formed from the characters of STR1. Both the strings can ...read more

Q93. Count Set Bits

You are given a positive integer ‘N’. Your task is to find the total number of ‘1’ in the binary representation of all the numbers from 1 to N.

Since the count of ‘1’ can be huge, you are required...read more

Q94. Fishmonger

A fishmonger wants to bring his goods from port to the market. On his route, he has to traverse an area with many states. He has to pay a toll at each border.

He is a good businessman. He wants to cho...read more

Q95. First negative integer in every window of size “k”

You have been given an array of integers 'ARR' and an integer ‘K’. You need to find the first negative integer in each window of size ‘K’.

Note :

If a window do...read more

Q96. Trapping Rain Water

You have been given a long type array/list 'ARR' of size 'N'. It represents an elevation map wherein 'ARR[i]' denotes the elevation of the 'ith' bar. Print the total amount of rainwater that ...read more

Q97. Postorder Traversal

You are given the root node of a binary tree consisting of ‘N’ nodes. Your task is to return its postorder traversal. The postorder traversal of a binary tree is defined as a process of trav...read more

Q98. Langford pairing

You are given a positive integer N. Return a list of integers of size 2N containing all the integers from 1 to N (both inclusive) twice arranged according to Langford pairing. If no such pairing...read more

Q99. Alien Dictionary.

You have been given a sorted (lexical order) dictionary of an alien language. Write a function that finds the order of characters in the alien language. This dictionary will be given to you in ...read more