DSA · Theory

Introduction to Hashing

Theory

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Hashing (introduction to) is simple if you keep it on paper. Sara uses it for marks stored somehow in a viva board.

For Hashing (introduction to), Big-O is in play. Don’t blame it until you have traced marks stored somehow.

Without Hashing (introduction to), a viva board gets messy and marks stored somehow is hard to trust.

Hashing (introduction to) shows up in a viva board. Name marks stored somehow, not “a real-world scenario”.

Hashing (introduction to) miss — reciting names with no cost. Fix it before you talk about advanced DSA.

After Hashing (introduction to), Sara should still remember reciting names with no cost.

Viva for Hashing (introduction to): what it is → array vs list vs hash — one line each → the mistake (reciting names with no cost).

Exam tip

Board: marks stored somehow. Dry-run Hashing (introduction to). Name the trap: reciting names with no cost.

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

Introduction to Hashing — hash maps give average O(1) insert/lookup — dict in Python.

DefHashing (introduction to) — Sara uses it for marks stored somehow in a viva board.
RuleHashing (introduction to) → array vs list vs hash — one line each.
RememberHashing (introduction to) + Big-O (a viva board).
UseHashing (introduction to) in a viva board (marks stored somehow).
TrapHashing (introduction to) — reciting names with no cost.
ExHashing (introduction to) → marks stored somehow.