Paytm Software Engineer Interview Questions, Process, and Tips for Experienced

Find the number of rotations in a rotated sorted array.

• Use binary search to find the minimum element in the array.

• The number of rotations is equal to the index of the minimum element.

• If the minimum element is at index 0, then there are no rotations.

• If the array is not rotated, then the number of rotations is 0.

Modify a 2x2 matrix to replace row and column with 0 if a cell contains 0.

• Iterate through the matrix and find the cells with 0.

• Store the row and column index of the cells with 0 in separate arrays.

• Iterate through the row and column arrays and replace all elements with 0.

• Return the modified matrix.

Find row with max vowels in 2x2 matrix with first element of each row containing a vowel.

• Iterate through each row and count the number of vowels in it.

• Keep track of the row with max number of vowels.

• If first element of a row is a vowel, start counting from that element.

• Example: [['a', 'b'], ['e', 'i']] should return 2nd row.

SOLID principles are a set of five design principles for writing maintainable and scalable code.

• S - Single Responsibility Principle

• O - Open/Closed Principle

• L - Liskov Substitution Principle

• I - Interface Segregation Principle

• D - Dependency Inversion Principle

HashSet is a collection that stores unique elements by using a hash table.

• Elements are stored based on their hash code

• Uses hashCode() and equals() methods to check for duplicates

• Does not maintain insertion order

• Allows null values

• Example: HashSet set = new HashSet<>(); set.add("apple"); set.add("banana");