Hashing and maps in Python
Practice this questionWANT TO UNDERSTAND THE CONCEPT FIRST?Learn Hashing and maps in Python
Why it matters
Hashing is used for frequency counting, duplicate checks, and lookup optimization.
Problems to practice
- Valid Anagram
- Top K Frequent Elements
- First Non-Repeating Character
- Longest Consecutive Sequence
- Subarray Sum Equals K
Example: counts with dict
freq = {}
for ch in s:
freq[ch] = freq.get(ch, 0) + 1Interview guidance
Use a dictionary when lookup by key dominates the problem.
Adapted from 18_DSA_PYTHON.md · “3. Hashing and maps in Python”. Code examples are study fragments. Difficulty and core labels are editorial estimates; version-specific behavior should be checked against your project.