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TCS NQT GuideTCS NQT Coding Capability & AlgorithmsHashmaps and Frequency Counting Techniques

Hashmaps and Frequency Counting Techniques

Learn core concepts, essential formulas, and attempt practice questions designed on the latest TCS NQT testing patterns.

Key Concepts & Formulas

  • 1Hashmap: Stores key-value pairs with O(1) average search/insert times.
  • 2Frequency counting maps items to their counts to solve duplicates queries.

TCS NQT Style Practice Questions

Practice Question 1

What is the average search time complexity of a Hashmap?

A) O(1)
B) O(N)
C) O(log N)
D) O(N^2)

Correct Answer: A) O(1)

Step-by-step Solution: Hashmaps use hash tables to locate keys directly, achieving O(1) constant time complexity on average.

Practice Question 2

Find first non-repeating character in 'stress':

A) t
B) s
C) r
D) e

Correct Answer: A) t

Step-by-step Solution: Frequencies: s:3, t:1, r:1, e:1. Scanning from left: 's' repeats. 't' is the first character with frequency 1.

Study Pro-Tip

Use hashmaps when you need to solve O(N^2) search problems in O(N) time.

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