Top 250 Algorithms Interview Questions and Answers

The logic behind my code is to efficiently solve the given problem using algorithms and data structures.

• I analyze the problem requirements and constraints.

• I break down the problem into smaller subproblems.

• I choose appropriate algorithms and data structures.

• I implement the code using clean and readable syntax.

• I test and debug the code to ensure correctness and efficiency.

Delete duplicate is a function to remove duplicate entries from a list or array.

• Identify the duplicate entries in the list or array

• Use a loop to iterate through the list or array

• Remove the duplicate entries using the 'delete' keyword or a built-in function

• Ensure that the remaining entries are still in the correct order

OOPS concept - Inheritance

• Inheritance is a mechanism in OOPS where a new class is derived from an existing class

• The new class inherits all the properties and behavior of the existing class

• It allows code reusability and helps in creating a hierarchy of classes

• Example: A class 'Car' can be inherited by a class 'SUV' which will have all the properties of 'Car' and additional properties specific to 'SUV'

• Inheritance can be of different types - single, multiple, multilevel, hierarc...read more

The winner leetcode problem involves finding the candidate with the most votes in an election scenario.

• Iterate through the list of candidates and keep track of their votes

• Return the candidate with the highest number of votes

• Example: Input - ['Alice', 'Bob', 'Alice', 'Charlie', 'Bob'], Output - 'Alice'

Maximum subarray problem is to find the contiguous subarray with maximum sum in an array of integers.

• Use Kadane's algorithm to find the maximum subarray sum in linear time complexity.

• Initialize two variables, max_so_far and max_ending_here, to track the maximum sum so far and the maximum sum ending at the current index, respectively.

• Iterate through the array and update max_ending_here and max_so_far accordingly.

• Return max_so_far as the maximum subarray sum.

Answering questions related to string permutations, removing numbers, and checking for anagrams without using map data structure.

• To find permutations of a string, use recursion to swap characters at each position.

• To remove a specific character (e.g. '3') from a string, iterate through the string and build a new string without the character.

• To check for anagrams without using a map data structure, sort both strings and compare character by character.

RPN stands for Risk Priority Number and is used to prioritize risks based on severity, occurrence, and detection.

• RPN is calculated by multiplying the severity, occurrence, and detection scores of a risk.

• The severity, occurrence, and detection scores are typically rated on a scale of 1-10.

• The higher the RPN, the higher the priority of the risk.

• RPN can be used to prioritize which risks to address first.

• Example: A risk with a severity score of 8, occurrence score of 5, and detec...read more

As a CCR Operator, I maintain multiple parameters depending on the plant and equipment.

• The number of parameters varies depending on the plant and equipment being operated.

• Some common parameters include temperature, pressure, flow rate, and chemical levels.

• It is important to monitor and adjust these parameters to ensure safe and efficient operation.

• Regular maintenance and calibration of equipment is necessary to ensure accurate readings.

• Proper documentation of parameter readin...read more

To rotate an image in Python, use the Pillow library's rotate() method.

• Import the Image module from the Pillow library

• Open the image using the open() method

• Use the rotate() method to rotate the image by the desired angle

• Save the rotated image using the save() method

Greedy algorithms make the optimal choice at each step, while Divide and Conquer breaks a problem into smaller subproblems.

• Greedy algorithms select the best option at each step without considering the overall solution

• Divide and Conquer divides a problem into smaller subproblems, solves them recursively, and then combines the solutions

• Example of Greedy algorithm: Dijkstra's shortest path algorithm

• Example of Divide and Conquer: Merge Sort

Printing * using loops is a basic programming exercise.

• Use nested loops to print * in a pattern

• Use a for loop to print * in a straight line

• Use a while loop to print * until a certain condition is met

To find the largest number in an array, loop through the array and compare each element with a variable holding the current largest number.

• Initialize a variable with the first element of the array

• Loop through the array and compare each element with the variable holding the current largest number

• If the current element is larger than the variable, update the variable with the current element

• After the loop, the variable will hold the largest number in the array

Backtracking is a technique used to solve problems by trying out different solutions and undoing them if they fail.

• It is a trial-and-error approach to problem-solving

• It involves trying out different solutions and undoing them if they fail

• It is often used in algorithms for searching and optimization problems

• Examples include solving Sudoku puzzles and finding the shortest path in a maze

I would recommend restaurants based on the user's location, cuisine preferences, and popular restaurants in the area.

• Use the user's phone number to determine their location

• Ask the user for their cuisine preferences during the onboarding process

• Recommend popular restaurants in the area based on user reviews and ratings

• Use machine learning algorithms to personalize recommendations based on user behavior

Effective depth is the distance from the centroid of the tension reinforcement to the extreme compression fiber.

• It is a measure of the strength of a reinforced concrete beam or slab.

• It is calculated by subtracting the cover from the overall depth of the section.

• It is used to determine the amount of reinforcement required for a given load.

• For example, if the overall depth of a beam is 500mm and the cover is 50mm, the effective depth would be 450mm.

An Anagram program compares two strings to see if they are rearrangements of each other.

• Create a function that takes in two strings as input

• Remove any spaces and convert both strings to lowercase for accurate comparison

• Sort the characters in both strings and compare them to check if they are anagrams

• Return true if they are anagrams, false otherwise

Optimize O(n2) program to O(log n)

• Use binary search instead of linear search

• Divide and conquer approach can be used

• Implement efficient data structures like heap, AVL tree, etc.

• Reduce unnecessary iterations and comparisons

• Use memoization to avoid redundant calculations

To make a partition, you need to use a disk management tool or command prompt.

• Open Disk Management tool or Command Prompt

• Select the disk you want to partition

• Right-click on the unallocated space and select 'New Simple Volume'

• Follow the wizard to specify the size and format of the partition

• Alternatively, use the 'diskpart' command in Command Prompt to create a partition

Find peak in increasing and decreasing sequence

• Use binary search to find the peak element

• Compare the middle element with its neighbors to determine if it's a peak

• If the middle element is smaller than its left neighbor, search in the left half of the array

• If the middle element is smaller than its right neighbor, search in the right half of the array

Code to find LCM and HCF of two numbers

• Use Euclidean algorithm to find HCF

• LCM = (num1 * num2) / HCF

• Handle edge cases like zero or negative numbers

The question asks to find all the pairs present in an array of strings.

• Iterate through the array and compare each element with all other elements to find pairs.

• Store the pairs in a separate array or data structure.

• Consider the order of elements in pairs, i.e., (A, B) is different from (B, A).

Swapping two numbers without using a third variable in a program

• Use bitwise XOR operation to swap two numbers without using a third variable

• Example: int a = 5, b = 10; a = a ^ b; b = a ^ b; a = a ^ b; // Now a = 10, b = 5

• Ensure the numbers are not the same to avoid getting 0 as a result

Code to find maximum in an array of strings

• Iterate through the array and compare each element to find the maximum

• Use a variable to store the current maximum value and update it as needed

• Consider converting string elements to numbers if necessary for comparison

To cover the range of weights from 1-40 kgs, select weights in powers of 2.

• Select weights in powers of 2: 1, 2, 4, 8, 16, 32

• These weights can cover the complete range from 1-40 kgs

• Example: 1 kg + 2 kg + 4 kg + 8 kg + 16 kg + 32 kg = 63 kgs

Designing a search engine and measuring its success involves understanding user needs and behavior, optimizing search algorithms, and tracking key metrics.

• Identify user needs and behavior through user research and data analysis

• Optimize search algorithms to provide relevant and accurate results

• Track key metrics such as click-through rate, bounce rate, and conversion rate

• Continuously iterate and improve the search engine based on user feedback and data analysis

• Ensure the search...read more

Find the longest substring in a string without repeating characters.

• Use a sliding window approach to iterate through the string.

• Keep track of the characters seen so far in a set.

• Update the start of the window when a repeating character is encountered.

• Calculate the length of the current substring and update the longest substring found.

• Repeat until the end of the string is reached.

LSCS stands for Lower Segment Cesarean Section, a surgical procedure to deliver a baby through an incision in the mother's abdomen and uterus.

• LSCS is commonly performed when a vaginal delivery is not possible or safe for the mother or baby.

• It is also known as C-section.

• The incision is usually made in the lower part of the abdomen, below the bikini line.

• LSCS may be planned (elective) or done as an emergency procedure.

• After the baby is delivered, the incision is closed with sti...read more

Code to print even and odd numbers

• Use a loop to iterate through numbers

• Check if the number is even or odd using modulus operator

• Print the number accordingly

BF and PAL are both types of eyeglass lenses used to correct vision, but they have different designs and purposes.

• BF stands for Bifocal lenses, which have two distinct areas for near and distance vision.

• PAL stands for Progressive Addition Lenses, which have a gradual transition of power for different distances.

• BF lenses have a visible line separating the two areas, while PAL lenses have a seamless design.

• BF lenses are typically used for presbyopia, while PAL lenses are used f...read more

Search for a target value in a rotated sorted array.

• Use binary search to find the pivot point where the array is rotated.

• Determine which half of the array the target value lies in based on the pivot point.

• Continue binary search in the appropriate half of the array to find the target value.

Use a loop to iterate through the array and check if each element is an even number.

• Iterate through the array using a loop

• Check if each element is divisible by 2 without a remainder

• Store the even numbers in a separate array or print them out

Convert roman to int number

• Create a dictionary of roman numerals and their integer values

• Iterate through the roman numeral string and add corresponding integer values

• Subtract twice the value of previous numeral if it is smaller than current numeral

The question asks to find the frequency of a specific string in a large paragraph.

• Use a loop to iterate through each word in the paragraph

• Compare each word with the given string

• Keep a count of the number of times the string appears

If dist(u,v)>n/2 in an undirected graph, there exists a vertex x such that removing x makes u and v go to different connected components.

• Find the shortest path between u and v

• If the path length is greater than n/2, then there must be a vertex x on the path

• Removing x will separate u and v into different connected components

Find the largest sub set in a list of strings

• Iterate through the list of strings and keep track of the length of each subset

• Compare the lengths of subsets to find the largest one

• Return the largest subset

For an odd-sized grid, there cannot be a Hamiltonian cycle in the graph.

• A Hamiltonian cycle is a path that visits every vertex exactly once and ends at the starting vertex.

• In an n*n grid, there are n^2 vertices and each vertex has degree 4.

• For an odd n, the total degree of all vertices is odd, which means there cannot be a Hamiltonian cycle.

Count the number of islands in a binary matrix.

• Traverse the matrix and for each 1 encountered, perform DFS to mark all connected 1s as visited.

• Increment the island count for each new DFS traversal.

• Use a visited matrix to keep track of visited cells.

• Consider diagonal cells as connected if required.

• Optimize by using Union-Find data structure.

To swap the value of two variables without using a third variable, use arithmetic operations.

• Use addition and subtraction to swap values

• Example: a = 5, b = 10. a = a + b (a = 15), b = a - b (b = 5), a = a - b (a = 10)

Find the duplicate number in an array of 10 numbers with only 2 steps.

• Use a hash set to keep track of visited numbers.

• Iterate through the array and check if the number is already in the set.

• If it is, then it is the duplicate number.

• If not, add it to the set.

• At the end, the duplicate number will be found.

A program to calculate the sum of numbers.

• Create a variable to store the sum.

• Iterate through the numbers and add each number to the sum.

• Return the sum.

Given a chessboard, find the maximum number of squares present.

• Start with the smallest square and count all possible squares

• Use the formula n*(n+1)*(2n+1)/6 to find the total number of squares in an n x n chessboard

• Add up the squares of all sizes from 1 to n to get the maximum number of squares

• For example, an 8 x 8 chessboard has 204 squares

Check if two queens on a chessboard can kill each other

• Iterate through each queen's position and check if they are in the same row, column, or diagonal

• If any two queens are in the same row, column, or diagonal, return True

• Otherwise, return False

Given an array of numbers, find a subset of numbers whose sum is zero.

• Use a combination of numbers from the array to find subsets whose sum is zero.

• Iterate through all possible combinations of numbers and check if their sum is zero.

• Consider using recursion or backtracking to generate all possible combinations.

• Optimize the solution by using memoization or dynamic programming to avoid redundant calculations.

Boosting is an ensemble learning technique that combines multiple weak models to create a strong model.

• Boosting iteratively trains weak models on different subsets of data

• Each subsequent model focuses on the misclassified data points of the previous model

• Final prediction is made by weighted combination of all models

• Examples include AdaBoost, Gradient Boosting, XGBoost

Worst case analysis is a method used to determine the maximum possible performance or behavior of a system under extreme conditions.

• Worst case analysis involves identifying the most unfavorable conditions that a system may encounter.

• It helps in ensuring that the system will still function correctly even under the worst possible circumstances.

• This analysis is important for designing reliable systems that can handle extreme scenarios.

• For example, in hardware design, worst case ...read more

Given a rotated array, find a number efficiently.

• Use binary search to find the pivot point where the array is rotated.

• Divide the array into two subarrays and perform binary search on the appropriate subarray.

• Handle the case when the target number is at the pivot point.

Parameters for designing restaurant recommendation algorithm for Swiggy

• User's location and distance from the restaurant

• User's previous orders and ratings

• Restaurant's popularity and ratings

• Cuisine type and availability

• Time of day and day of the week

• Special offers and discounts

• Delivery time and availability

• User's dietary preferences and restrictions