Perfios Software Solutions Senior Technical Team Member Interview Questions and Answers

Implementing a palindrome check in Java without using the reverse() function.

• Create a function that takes a string as input.

• Use two pointers, one starting from the beginning of the string and the other from the end.

• Compare characters at the two pointers and move them towards each other until they meet or cross.

• If all characters match, the string is a palindrome.

• Example: 'racecar' is a palindrome.

• Example: 'hello' is not a palindrome.

Rotate an array of strings by n positions

• Create a new array and copy elements from original array starting from index n to the end, then copy elements from index 0 to n-1

• Alternatively, you can use array slicing to achieve the rotation

• Example: Original array ['a', 'b', 'c', 'd', 'e'], rotate by 2 positions would result in ['c', 'd', 'e', 'a', 'b']

The algorithm to reverse a singly linked list involves iterating through the list and changing the pointers to reverse the direction of the links.

• Start with three pointers: current, previous, and next.

• Iterate through the list, updating the next pointer to point to the previous node.

• Move the previous pointer to the current node and the current pointer to the next node.

• Continue until the end of the list is reached, then update the head of the list to the last node visited.

Use counting method to sort array of strings with 0's and 1's.

• Create a count array to store the frequency of 0's and 1's.

• Update the original array based on the count array.

• Example: Input array - ['0', '1', '0', '1', '1'], Output array - ['0', '0', '1', '1', '1']

HTTPS provides secure communication over the internet using encryption, while HTTP does not.

• HTTPS uses SSL/TLS encryption to secure data transmission, while HTTP does not.

• HTTPS URLs begin with 'https://' and use port 443, while HTTP URLs begin with 'http://' and use port 80.

• HTTPS ensures data integrity and authentication, while HTTP does not provide these security measures.

SQL query to retrieve data from employee table

• Use SELECT statement to retrieve data

• Specify the columns you want to retrieve

• Use FROM clause to specify the table name

• Add any conditions using WHERE clause if needed

Use ORDER BY and LIMIT to get last entry in SQL query

• Use ORDER BY column_name DESC to sort in descending order

• Use LIMIT 1 to get only the last entry