DSA · Theory

Hash Table vs STL Map

Theory

209/810

Hash Table vs STL Map is a DSA topic. In plain words you use it for name → phone in a diary. Don’t start with a slogan — start with that picture.

Smallest example: key % size + collision plan. Type it, run it, and say what you see. If you can do that from memory, you know Hash Table vs STL Map.

From the example next to this theory: Hash Table vs STL Map — hash maps give average O(1) insert/lookup — dict in Python.

Trap — bad hash → pile-up. Fix that before you talk about advanced DSA.

Viva — what is Hash Table vs STL Map? Then show key % size + collision plan. Then name the trap.

Exam tip

What is Hash Table vs STL Map? Show this: key % size + collision plan. Trap: bad hash → pile-up.

freq = {}
for ch in "banana":
    freq[ch] = freq.get(ch, 0) + 1
print(freq)
print(freq.get("a"), freq.get("z", 0))

Hash Table vs STL Map — hash maps give average O(1) insert/lookup — dict in Python.