1000+ Software Developer Interview Questions and Answers for Freshers

The task is to find a string of minimal length that includes every possible string of N digits with digits ranging from 0 to K as substrings.

• Generate all possible strings of N digits with digits from 0 to K

• Concatenate these strings in a way that all are substrings of the final string

• Return 1 if the final string contains all possible strings, else return 0

Remove alternate nodes from a singly linked list of integers.

• Traverse the linked list and skip every alternate node while updating the next pointers.

• Make sure to handle cases where there are less than 3 nodes in the list.

• Update the next pointers accordingly to remove alternate nodes.

• Example: Input: 10 20 30 40 50 60 -1, Output: 10 30 50

The problem is to find the maximum number of fruits the Ninja can put in both baskets after satisfying given conditions.

• The Ninja can start at any tree and end at any tree, but cannot skip a tree.

• He can pick one fruit from each tree until he cannot, i.e., when he has to pick a fruit of the third type.

• The restriction is that each basket can have only one type of fruit.

• We need to find the maximum number of fruits that can be put in both baskets.

The task is to sort an array of 0s, 1s, and 2s in increasing order.

• Use a three-pointer approach to partition the array into three sections: 0s, 1s, and 2s.

• Initialize three pointers: low, mid, and high. low points to the start of the array, mid points to the current element being processed, and high points to the end of the array.

• While mid <= high, perform the following checks: if arr[mid] == 0, swap arr[low] and arr[mid], increment low and mid. If arr[mid] == 1, increment mid...read more

The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up numbers equals the given 'target' sum.

• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the number of ways to achieve each sum with the given number of dice.

• Iterate through the dice and faces to calculate the number of ways to reach each sum.

• Return the result modulo 10^9 + 7.

• Optimize the solution to use no more than O(S) extra space by u...read more

Find the sum of numbers divisible by 2 or 3 from a given list of numbers.

• Iterate through the list of numbers and check if each number is divisible by 2 or 3.

• If a number is divisible by 2 or 3, add it to the sum.

• Return the final sum as the output.

Implement a program to compress a string by replacing consecutive duplicates with the count of repetitions.

• Iterate through the string and keep track of consecutive characters and their counts.

• Replace consecutive duplicates with the count of repetitions.

• Ensure the count of repetitions is ≤ 9.

• Return the compressed string.

Count pairs in an array with a specific absolute difference.

• Iterate through the array and for each element, check if the element + K or element - K exists in the array.

• Use a hash set to store elements for constant time lookups.

• Keep track of the count of valid pairs found.

Sort an array of 0s and 1s in linear time without using additional arrays.

• Iterate through the array and maintain two pointers, one for 0s and one for 1s.

• Swap elements at the two pointers based on the current element being 0 or 1.

• Continue this process until the entire array is sorted in place.

Count the number of distinct ways to climb a staircase with a certain number of steps using either one or two steps at a time.

• Use dynamic programming to solve this problem efficiently.

• Keep track of the number of ways to reach each step by considering the number of ways to reach the previous two steps.

• Return the result modulo 10^9+7 to handle large outputs.

• Example: For N=4, the distinct ways to climb are {(0,1,2,3,4)}, {(0,1,2,4)}, {(0,2,3,4)}, {(0,1,3,4)}, and {(0,2,4)} total...read more

Find the maximum sum of non-adjacent elements in an array.

• Use dynamic programming to keep track of the maximum sum at each index, considering whether to include the current element or skip it.

• At each index, the maximum sum is either the sum of the current element and the element two positions back, or the sum at the previous index.

• Iterate through the array and update the maximum sum at each index accordingly.

• Return the maximum sum obtained at the last index as the final resul...read more

Calculate the N-th term of a Geometric Progression series given the first term, common ratio, and term position.

• Use the formula A * R^(N-1) to find the N-th term of the GP series.

• Remember to return the result modulo 10^9 + 7 as the term can be very large.

• Handle multiple test cases efficiently by iterating through each case.

Determine if an array can be transformed into a non-decreasing array by modifying at most one element.

• Iterate through the array and check if there are more than one decreasing elements.

• If there is only one decreasing element, check if modifying it can make the array non-decreasing.

• Return true if the array can be made non-decreasing by modifying at most one element, otherwise false.

Calculate the total volume of water that can be trapped in a 2-D elevation map after rain.

• Iterate over the matrix and find the maximum height on the borders.

• Calculate the water trapped at each cell by finding the difference between the cell's height and the minimum of its neighboring maximum heights.

• Sum up the trapped water for all cells to get the total volume of water trapped.

The task is to print two strings in an alternating sequence by indices.

• Iterate through both strings simultaneously and append characters alternately

• Handle the case where one string is longer than the other

• Use two pointers to keep track of the current index in each string

Check if a given matrix is idempotent by verifying if M * M = M.

• Iterate through the matrix and multiply it with itself to check if it equals the original matrix.

• If the condition M * M = M is satisfied, then the matrix is idempotent.

• If the condition is not satisfied, then the matrix is not idempotent.

Count the total number of palindromic substrings in a given string.

• Iterate through each character in the string and expand around it to find palindromic substrings.

• Use dynamic programming to store the results of subproblems to avoid redundant calculations.

• Consider both odd and even length palindromes while counting.

• Example: For input 'abbc', the palindromic substrings are ['a', 'b', 'b', 'c', 'bb'], totaling 5.

Calculate the sum of minimum and maximum elements of all subarrays of size K in an array.

• Iterate through the array and maintain a deque to store the indices of elements in the current window of size K.

• Keep track of the minimum and maximum elements in the current window using the deque.

• Calculate the sum of minimum and maximum elements for each subarray of size K and return the total sum.

Find the duplicate number in an array of integers from 0 to N-2.

• Iterate through the array and keep track of the frequency of each number using a hashmap.

• Return the number with a frequency greater than 1 as the duplicate number.

• Alternatively, use Floyd's Tortoise and Hare algorithm to find the duplicate number in O(N) time and O(1) space.

Find the longest palindromic substring in a given string, returning the rightmost one if multiple substrings are of the same length.

• Iterate through each character in the string and expand around it to find palindromic substrings

• Keep track of the longest palindromic substring found so far

• Return the rightmost longest palindromic substring

Find the fourth largest element in an array, return -2147483648 if not enough distinct elements.

• Sort the array in descending order

• Return the fourth element if it exists, else return -2147483648

The task is to find the length of the longest palindromic subsequence in a given string.

• A subsequence is a sequence generated from a string after deleting some or no characters of the string without changing the order of the remaining string characters.

• A string is said to be palindrome if the reverse of the string is the same as the actual string.

• Find the longest palindromic subsequence by considering all possible subsequences of the given string.

• Use dynamic programming to ef...read more

Find the length of the longest subarray with zero sum in an array of integers.

• Iterate through the array and keep track of the running sum using a hashmap.

• If the running sum is seen before, the subarray between the current index and the previous index with the same sum is a subarray with zero sum.

• Update the length of the longest subarray with zero sum as you iterate through the array.

• Example: For arr1 = [1, -1, 3, 2, -2, -3, 3], the longest subarray with zero sum is [3, 2, -2,...read more

Reschedule at most K presentations to maximize longest gap without overlap.

• Iterate through presentations and calculate the gap between each pair of presentations

• Sort the presentations by their start times and keep track of the longest gap

• Reschedule at most K presentations to maximize the longest gap without overlap

The task is to check whether a given string is a palindrome or not, considering only alphabets and numbers and ignoring symbols and whitespaces.

• Convert the string to lowercase and remove all symbols and whitespaces.

• Reverse the modified string and compare it with the original string.

• If they are equal, then the string is a palindrome.

• If not, then the string is not a palindrome.

Sort an array of 0s, 1s, and 2s in linear time complexity.

• Use three pointers to keep track of the positions of 0s, 1s, and 2s in the array.

• Iterate through the array and swap elements based on the values encountered.

• Maintain left pointer for 0s, right pointer for 2s, and current pointer for traversal.

• Example: If current element is 0, swap it with element at left pointer and increment both pointers.

Implement a function to delete a node from a linked list at a specified position.

• Traverse the linked list to find the node at the specified position.

• Update the pointers of the previous and next nodes to skip the node to be deleted.

• Handle edge cases such as deleting the head or tail of the linked list.

• Ensure to free the memory of the deleted node to avoid memory leaks.

Find the K-th permutation sequence of numbers from 1 to N.

• Generate all permutations of numbers from 1 to N using backtracking or next_permutation function.

• Sort the permutations in lexicographical order.

• Return the K-th permutation from the sorted list.

Calculate the number of ways Preeti can purchase items within budget, with at least one item quantity differing.

• Use dynamic programming to calculate the number of ways to purchase items within budget.

• Consider different scenarios where Preeti buys different quantities of each item.

• Return the result modulo 10^9 + 7 to handle large answers.

Calculate the sum of squares of the first N natural numbers for given test cases.

• Read the number of test cases 'T'

• For each test case, read the value of 'N'

• Calculate the sum of squares of the first 'N' natural numbers

• Output the result for each test case

The problem involves finding the number of ways to tile a 2xN board using 2x1 tiles.

• Use dynamic programming to solve this problem efficiently.

• Define a recursive function to calculate the number of ways to tile the board.

• Consider both horizontal and vertical placements of tiles.

• Implement the function to handle large values of N using modulo arithmetic.

• Example: For N = 4, the number of ways to tile the board is 5.

The task is to print the right view of a binary tree, representing nodes visible from the right side in top-to-bottom order.

• Traverse the tree level by level and keep track of the rightmost node at each level

• Print the rightmost node of each level to get the right view of the tree

• Use a queue for level order traversal and a map to store the rightmost nodes

Implement a cache with insert, update, and retrieve operations, returning results of retrieve operations in order.

• Create a cache data structure with specified size 'N'.

• Implement insert and update operations based on the given criteria.

• For retrieve operation, return the value associated with the 'U_ID' if present, else return -1.

• Handle cases where the cache is full and least frequently used items need to be removed.

• Return the results of all retrieve operations in the order the...read more

The task is to count the total number of '1' in the binary representation of all numbers from 1 to N.

• Convert each number from 1 to N into its binary representation

• Count the number of '1' bits in each binary representation

• Sum up the counts of '1' bits for all numbers

• Return the sum modulo 1e9+7

Validate IFSC code based on given rules and return True or False for each test case.

• Check if the code is 11 characters long.

• Verify the first four characters are uppercase alphabets.

• Ensure the fifth character is '0'.

• Validate that the last six characters are alphanumeric.

Determine the minimum number of conference rooms needed to schedule meetings without overlap.

• Sort the meetings by start time.

• Iterate through the meetings and keep track of the rooms in use.

• If a meeting starts after another ends, it can reuse the same room.

• If a meeting starts before another ends, a new room is needed.

• Return the maximum number of rooms in use at any point.

Calculate the earliest day on which Ninja can buy all candies with special offers.

• Iterate through each day and check if any special offer is available for candies Ninja wants to buy

• Keep track of the minimum day on which Ninja can buy all candies

• Consider both regular price and sale price of candies

Count the occurrence of each word in a given string.

• Split the string into words using spaces as delimiters.

• Use a hashmap to store the count of each word.

• Iterate through the words and update the count in the hashmap.

• Output each unique word with its occurrence count.

The task is to check if one string can be converted into another string by cyclically rotating it to the right any number of times.

• Iterate through each character of the first string and check if it matches the corresponding character in the second string after a certain number of cyclic rotations.

• If all characters match for any number of cyclic rotations, then the first string can be converted into the second string.

• Use modulo arithmetic to handle cyclic rotations efficiently...read more

Check if a string is formed by interleaving two other strings.

• Iterate through characters of A, B, and C simultaneously to check if C is formed by interleaving A and B.

• Use dynamic programming to efficiently solve the problem.

• Handle edge cases like empty strings or unequal lengths of A, B, and C.

• Example: A = 'aab', B = 'abc', C = 'aaabbc' should return True.

Find the minimum number of dice throws required to reach the last cell on a 'Snake and Ladder' board.

• Start from the bottom left cell and move according to dice outcomes (1-6).

• Utilize snakes and ladders to reach the last cell faster.

• Keep track of the minimum number of throws required to reach the last cell.

• If unreachable, return -1 as output.

The goal is to determine the maximum profit that can be achieved by buying and selling stocks on different days.

• Iterate through the stock prices and buy on days when the price is lower than the next day, and sell on days when the price is higher than the next day.

• Calculate the profit by summing up the differences between buying and selling prices.

• Repeat the process for each test case and output the maximum profit achieved.

• Example: For prices [7, 1, 5, 3, 6, 4], buy on day 2 a...read more

The problem involves selecting the smallest character from the first 'K' characters of a string and appending it to a new string until the original string is empty.

• Iterate through the string, selecting the smallest character from the first 'K' characters each time.

• Remove the selected character from the original string and append it to the new string.

• If fewer than 'K' characters remain, sort and append them in order.

• Repeat the process until the original string is empty.

The task is to find the second largest element in an array of integers.

• Iterate through the array and keep track of the largest and second largest elements.

• Initialize the largest and second largest variables with the first two elements of the array.

• Compare each element with the largest and second largest variables and update them accordingly.

• Return the second largest element at the end.

Calculate the maximum number of unique vehicle registrations based on given constraints.

• Parse input for number of test cases, district count, letter ranges, and digit ranges.

• Calculate the total number of unique registrations based on the given constraints.

• Output the maximum number of unique vehicle registrations for each test case.

The question asks whether it is possible to sort an array by choosing a continuous subarray and reversing it.

• Check if the array is already sorted. If yes, return true.

• Find the first and last elements of the subarray that needs to be reversed.

• Check if the subarray is in non-decreasing order. If yes, return true.

• Check if the elements after the subarray are in non-increasing order. If yes, return true.

• Otherwise, return false.

Find the intersection of two integer arrays/lists in the order they appear in the first array/list.

• Iterate through the elements of the first array/list and check if they exist in the second array/list.

• Use a hash set to store elements of the first array/list for efficient lookups.

• Print the common elements in the order they appear in the first array/list.