Data Structures

• HashMaps / Dictionaries: insertion, deletion, lookup, counting frequencies.
• Arrays & Strings: sliding window, two pointers, prefix sums.
• Linked Lists, Trees, Graphs basics if asked.

Algorithms

• Sorting and searching.
• Hash-based problems (two-sum, subarrays with sum k, etc.).
• Recursion and backtracking for small problems.

SQL & Database

• Complex joins, aggregations, subqueries.
• Optimizing queries.
• Data transformation (ETL) logic.

The interview was very tough. It happened for an hour and asked questions about LeetCode.