1500+ Software Engineer Interview Questions and Answers for Freshers

Find the index of the first occurrence of string A in string B.

• Iterate through string B and check if a substring of length equal to A matches A.

• Return the index of the first occurrence of A in B, or -1 if not found.

Generate and print all possible permutations of a given input string.

• Use recursion to generate all permutations by swapping characters in the string.

• Maintain a visited array to keep track of characters already used in a particular permutation.

• Print each permutation as it is generated.

• Handle duplicate characters by skipping swapping if the character is already in the current position.

Identify all prime numbers less than or equal to a given positive integer N.

• Iterate from 2 to N and check if each number is prime

• Use the Sieve of Eratosthenes algorithm for efficient prime number identification

• Optimize by only checking up to the square root of N for divisors

Reverse a given stack of integers using recursion without using extra space or loops.

• Use recursion to pop all elements from the original stack and store them in function call stack

• Once the stack is empty, push the elements back in reverse order using recursion

• Use the top(), pop(), and push() methods to manipulate the stack

The Water Jug Problem involves determining if a specific amount of water can be measured using two jugs of different capacities.

• Start by considering the constraints and limitations of the problem.

• Think about how the operations allowed can be used to reach the target measurement.

• Consider different scenarios and test cases to come up with a solution.

• Implement a function that takes the capacities of the jugs and the target measurement as input and returns True or False based on ...read more

Generate all possible valid parentheses configurations with N pairs.

• Use backtracking to generate all possible combinations of parentheses.

• Keep track of the number of open and close parentheses used.

• Add '(' if there are remaining open parentheses, and add ')' if there are remaining close parentheses.

To win the coin placement game, start by placing a coin in the center and mirror your opponent's moves.

• Place your first coin in the center of the table.

• After your opponent places a coin, identify the position relative to the center.

• Reflect their move across the center point to maintain symmetry.

• This strategy ensures that you always have a valid move until the table is full.

Find the maximum difference between any two elements in an array and determine if it is even or odd.

• Iterate through the array to find the maximum and minimum elements.

• Calculate the difference between the maximum and minimum elements.

• Check if the difference is even or odd and return the result.

Minimum number of airplanes needed to get one airplane all the way around the world and return safely to the airport.

• To achieve this, we need 3 airplanes in total.

• The first airplane flies halfway around the world, then transfers half of its fuel to the second airplane.

• The first airplane then returns to the airport, while the second airplane continues to fly the remaining half of the journey.

• When the second airplane reaches the destination, it transfers all its fuel to the thi...read more

The task is to determine the total number of ways to make change for a specified value using given denominations.

• Create a dynamic programming table to store the number of ways to make change for each value up to the target value.

• Iterate through each denomination and update the table accordingly based on the current denomination.

• The final value in the table will represent the total number of ways to make change for the target value.

• Consider edge cases such as when the target v...read more

Calculate the Nth Fibonacci number efficiently using dynamic programming.

• Use dynamic programming to store previously calculated Fibonacci numbers to avoid redundant calculations.

• Start with base cases F(1) and F(2) as 1, then iterate to calculate F(N) efficiently.

• Time complexity can be optimized to O(N) using dynamic programming.

• Example: For N = 5, the 5th Fibonacci number is 5.

Program for Fibonacci series for n terms with user input.

• Take user input for n

• Initialize variables for first two terms of Fibonacci series

• Use a loop to generate the series up to n terms

• Print the series

4 people with different crossing times need to cross a bridge with one torch. Only 2 can cross at a time. What's the minimum time?

• The person with the longest time should always be accompanied by someone else

• The two fastest people should cross together to save time

• The torch needs to be brought back to the starting side every time two people cross

• The total time taken will be the sum of all individual crossing times

Modify a boolean matrix such that if any element is 1, set its entire row and column to 1.

• Iterate through the matrix and mark rows and columns to be modified

• Use additional arrays to keep track of rows and columns to be modified

• Update the matrix in-place based on the marked rows and columns

Print the left view of a binary tree given in level order form.

• Traverse the tree level by level and print the first node of each level (leftmost node).

• Use a queue to keep track of nodes at each level.

• Time complexity should be O(n) where n is the number of nodes in the tree.

Identify the missing integer in an array of binary strings and return its binary representation without leading zeros.

• Iterate through the binary strings to convert them to integers and find the missing number using the formula for sum of integers from 0 to N.

• Calculate the sum of all integers from 0 to N using the formula (N*(N+1))/2 and subtract the sum of the integers in the array to find the missing number.

• Convert the missing integer to binary representation and return it a...read more

Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.

• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, it indicates the presence of a cycle in the linked list.

• If one of the pointers reaches the end of the list (null), it means there is no cycle.

Given an arithmetic expression, place parentheses to maximize the value of the expression.

• Identify the operators in the expression ('+', '-', '*').

• Consider the precedence of operators to determine where to place parentheses.

• Calculate the value of the expression with different placements of parentheses to find the maximum value.

Reverse a singly linked list of integers.

• Iterate through the linked list and reverse the pointers to point to the previous node instead of the next node.

• Keep track of the current, previous, and next nodes while traversing the list.

• Update the head of the linked list to be the last node encountered during traversal.

Merge nodes between zeroes in a linked list to store the sum of included nodes.

• Traverse the linked list and keep track of sum between zeroes

• Merge nodes between zeroes by updating the sum in the merged node

• Handle edge cases like empty list or single node between zeroes

• Ensure the list starts and ends with a zero

Calculate the total coverage of zeros in a binary matrix based on adjacent ones in a defined neighborhood.

• Matrix Traversal: Iterate through each cell in the N x M matrix to identify zeros.

• Neighbor Counting: For each zero, check its top, bottom, left, and right neighbors to count the number of adjacent ones.

• Boundary Conditions: Ensure that checks for neighbors do not go out of matrix bounds to avoid errors.

• Example: In a 3x3 matrix with zeros at (0,0), (0,2), and (1,1), the cov...read more

The task is to implement a wildcard pattern matching algorithm that checks if a given wildcard pattern matches a given text.

• The wildcard pattern can include the characters '?' and '*'

• '?' matches any single character

• '*' matches any sequence of characters (sequence can be of length 0 or more)

• The matching should cover the entire text, not partial text

• Implement a function that takes the wildcard pattern and the text as input and returns True if the text matches the pattern, False...read more

Check if two binary trees are mirrors of each other based on specific criteria.

• Compare the roots of both trees.

• Check if the left subtree of the first tree is the mirror of the right subtree of the second tree.

• Verify if the right subtree of the first tree is the mirror of the left subtree of the second tree.

Given a 2D array, find elements where sum of cube of digits equals element itself and return (i * i + j * j) value.

• Iterate through the 2D array and check if the sum of cube of digits equals the element itself.

• Calculate (i * i + j * j) for such elements and return the values.

• If no such element exists, return -1.

Implement a function to multiply two sparse matrices and return the resulting matrix.

• Create a function that takes two sparse matrices as input and returns the resulting matrix after multiplication.

• Iterate through the non-zero elements of the matrices to perform the multiplication efficiently.

• Ensure to handle the sparse nature of the matrices to optimize the multiplication process.

• Consider the constraints provided to ensure the function works within the specified limits.

• Test t...read more

Find the maximum sum path in a matrix from top row to bottom row by moving down or diagonally.

• Use dynamic programming to keep track of maximum sum at each cell.

• At each cell, consider the maximum sum from the cell above, left diagonal, and right diagonal.

• Add the current cell value to the maximum of the three possibilities.

• Repeat this process for all cells in the matrix to find the maximum sum path.

Sort a Singly Linked List based on actual values instead of absolute values.

• Traverse the linked list and store the values in an array.

• Sort the array based on actual values.

• Update the linked list with the sorted values.