Larsen & Toubro interview prep

DSAEasy

Which of these runs in O(log n) time on n items?

1. Binary search for a key in a sorted array
2. Finding the largest value in an unsorted array
3. Comparing every pair of elements
4. Printing every element

This topic is named in a candidate’s interview report: L&T-NxT graduate engineer trainee interview, 2021, on GeeksforGeeks.

DSAEasy

Which of these is a non-linear data structure?

1. Array
2. Tree
3. Queue
4. Linked list

This topic is named in a candidate’s interview report: L&T-NxT graduate engineer trainee interview, 2021, on GeeksforGeeks.

DSAEasy

When is a linked list a better choice than an array?

1. When you need fast access to the i-th element
2. When you often insert or delete in the middle at a position you already hold, and do not need indexing
3. When memory per element must be as small as possible
4. When the data must be sorted by binary search

This topic is named in a candidate’s interview report: L&T-NxT graduate engineer trainee interview, 2021, on GeeksforGeeks.

PythonEasy

A valid password has at least 8 characters, a digit and an upper-case letter. What does this print?

def valid(p):
    return (len(p) >= 8
            and any(c.isdigit() for c in p)
            and any(c.isupper() for c in p))

print([valid(p) for p in ["Secret12", "secret123", "Short1A", "LONGPASSWORD"]])

1. [True, True, False, False]
2. [True, False, False, False]
3. [True, False, True, False]
4. [False, False, False, False]

This topic is named in a candidate’s interview report: L&T-NxT graduate engineer trainee interview, 2021, on GeeksforGeeks.

C and C++Medium

A std::vector is full and push_back is called. What happens, and what is the cost per push_back on average?

1. It links a new block without moving anything; O(log n)
2. It throws std::length_error
3. It allocates exactly one more slot each time; O(1) every time
4. It allocates a larger buffer (usually about twice as big) and moves the elements over; amortised O(1)

This topic is named in a candidate’s interview report: L&T-NxT graduate engineer trainee interview, 2021, on GeeksforGeeks.

C and C++Medium

How do lookups in std::map and std::unordered_map compare?

1. map is O(1) and unordered_map is O(log n)
2. Both are hash tables, O(1)
3. map is a balanced tree, O(log n) and kept in key order; unordered_map is a hash table, O(1) on average
4. Both are O(n), because they scan their keys

This topic is named in a candidate’s interview report: L&T-NxT graduate engineer trainee interview, 2021, on GeeksforGeeks.

DBMS and SQLMedium

What does a FULL OUTER JOIN of tables A and B return?

1. Only rows that match in both
2. Every row from both tables: matched rows joined, and unmatched rows from either side with NULLs for the other side's columns
3. Every row from A only
4. Every combination of rows from A and B

This topic is named in a candidate’s interview report: L&T-NxT graduate engineer trainee interview, 2021, on GeeksforGeeks.

DBMS and SQLEasy

What makes a DBMS relational (an RDBMS)?

1. It stores data in files
2. It needs no schema
3. It can only hold one table
4. It keeps data in tables of rows and columns related through keys, enforces integrity constraints and is queried with SQL

This topic is named in a candidate’s interview report: Graduate engineer trainee on-campus interview, 2022, on GeeksforGeeks.

Machine learningEasy

How are artificial intelligence, machine learning and deep learning related?

1. They are three names for the same thing
2. Deep learning is a kind of machine learning (many-layered neural networks), and machine learning is one way of building AI
3. Machine learning includes AI
4. Deep learning has nothing to do with neural networks

This topic is named in a candidate’s interview report: Graduate engineer trainee on-campus interview, 2022, on GeeksforGeeks.