DSA · Theory

Hash Table vs STL Map

Theory

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Hash Table vs STL Map sits in a diary. Riya’s job is name → phone. Write that first.

Hash Table vs STL Map on the board — key % size + collision plan. Then say what name → phone looks like after.

Without Hash Table vs STL Map, a diary gets messy and name → phone is hard to trust.

Hash Table vs STL Map shows up in a diary. Name name → phone, not “a real-world scenario”.

Don’t do this with Hash Table vs STL Map: bad hash → pile-up. Interviewers spot it in ten seconds.

After Hash Table vs STL Map, Riya should still remember bad hash → pile-up.

Viva for Hash Table vs STL Map — what it is → key % size + collision plan → the mistake (bad hash → pile-up).

Exam tip

Say Hash Table vs STL Map in one breath, then key % size + collision plan, then 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.