Top 250 Algorithms Interview Questions and Answers

The task is to determine if a given 9x9 matrix can be filled with digits 1-9 to form a valid Sudoku solution.

• Iterate through each cell in the matrix.

• For each empty cell, try filling it with a digit from 1-9 and check if it satisfies the Sudoku condit...read more

The Knapsack Problem involves maximizing profit by choosing which items to make with limited resources.

• Understand the problem statement and constraints provided.

• Implement a dynamic programming solution to solve the Knapsack Problem efficiently.

• Iterat...read more

Algorithm to find Nth-to-Last element in a singly linked list of unknown length

• Traverse the list and maintain two pointers, one at the beginning and one at Nth node from beginning

• Move both pointers simultaneously until the second pointer reaches the ...read more

The task is to find the maximum sum of node values of any subtree that is a Binary Search Tree(BST).

• Traverse the binary tree in a bottom-up manner

• For each node, check if it forms a BST and calculate the sum of its subtree

• Keep track of the maximum sum...read more

Finding the index value of a given element in an array of strings.

• Iterate through the array and compare each element with the given value.

• If a match is found, return the index of that element.

• If no match is found, return -1.

NMST stands for National Mathematics and Science Talent Examination.

• NMST is a competitive exam conducted for students in the field of mathematics and science.

• It aims to identify and nurture talented students in these subjects.

• The exam is open to stud...read more

A program to print name using an array of strings.

• Declare an array of strings with the name.

• Assign the name to the array.

• Loop through the array and print each string.

Efficiency is the ability to do something in a way that achieves maximum productivity with minimum wasted effort or expense.

• Efficiency is a measure of how well a system or process performs.

• It is often expressed as a percentage of the total input that...read more

Given a map of coffee shops and a person, find the closest n coffee shops to him.

• Use the person's location and calculate the distance to each coffee shop on the map.

• Sort the coffee shops by distance and return the closest n.

• Consider using a data stru...read more

Find the largest non-negative integer whose square is less than or equal to a given integer.

• Use binary search to efficiently find the square root of the given integer.

• Start with a range from 0 to the given integer and iteratively narrow down the rang...read more

Find total number of pairs in array that sum to given value.

• Use a hashmap to store frequency of each element in the array.

• Iterate through the array and check if (Sum - current element) exists in the hashmap.

• Increment count of pairs if found and updat...read more

GCD stands for Greatest Common Divisor. It is the largest positive integer that divides two or more numbers without leaving a remainder.

• GCD is used to find the highest common factor between two or more numbers.

• It is often used in mathematical calcula...read more

Count the total number of distinct subarrays with at most K odd elements in an array.

• Iterate through all subarrays and count the number of odd elements in each subarray.

• Use a hashmap to keep track of the count of distinct subarrays with at most K odd...read more

Find the minimum time required for 'K' painters to paint 'N' boards with given lengths.

• Use binary search to find the minimum and maximum possible time to paint all boards.

• Iterate through the possible time range and check if it is feasible to paint al...read more

Code for Fibonacci number using recursion

• Define a function that takes an integer as input

• If the input is 0 or 1, return the input

• Else, return the sum of the function called with input-1 and input-2

• Call the function with the desired input

Given a string of digits, find all potential valid IP addresses that can be formed from it.

• Split the string into four parts and check if each part is a valid IP segment (0-255).

• Use backtracking to generate all possible combinations of valid IP addres...read more

Find all subsets of a number set with a given sum

• Use a recursive approach to generate all possible subsets

• For each subset, calculate the sum and check if it matches the given number

• Store the subsets that satisfy the condition

Find Pythagorean triplets in an array of integers.

• Loop through the array and pick two numbers at a time.

• Calculate the sum of squares of the two numbers.

• Check if the sum is a perfect square.

• If yes, then it is a Pythagorean triplet.

• Repeat until all pos...read more

Find if a given string exists in a given matrix of characters

• Iterate through each character in the matrix and check if it matches the first character of the given string. If it does, perform a depth-first search to check if the rest of the string can...read more

Compare two version numbers to determine the latest version.

• Split the version numbers by '.' and compare each part from left to right.

• If a part in Version2 is greater than the corresponding part in Version1, Version2 is the latest.

• Handle cases where ...read more

Count the number of positive integral pairs (X, Y) that satisfy the given equation.

• Iterate through all possible values of X and calculate corresponding Y to check if the equation is satisfied.

• Optimize the solution by considering the constraints and p...read more

Given a graph with 'N' vertices and 'M' edges, determine if it can be colored using two colors without adjacent vertices sharing the same color.

• Use graph coloring algorithm like BFS or DFS to check if the graph can be colored with two colors without ...read more

The goal is to schedule jobs to maximize profit while meeting deadlines. Each job takes one unit of time and only one job can be scheduled at a time.

• Sort the jobs in decreasing order of profit

• Iterate through the sorted jobs and schedule them based on...read more

To find distinct elements in a list

• Create an empty set

• Iterate through the list and add each element to the set

• Return the set

Check if two strings are anagrams by comparing the sorted versions of the strings.

• Sort both strings and compare if they are equal.

• Use a hashmap to store the frequency of characters in each string and compare the maps.

• Ignore spaces and punctuation whe...read more

Algorithm for Snake and Ladders game

• Create a board with 100 squares

• Assign snakes and ladders to specific squares

• Roll a dice to move player's token on the board

• Check if the new position is a snake or ladder

• Repeat until a player reaches the final squar...read more

To avoid hash collisions, use a good hash function, increase the size of the hash table, and handle collisions using techniques like chaining or open addressing.

• Use a good hash function that distributes the keys evenly across the hash table.

• Increase ...read more