DSA · Theory

Introduction to Hashing

Theory

214/810

Introduction to Hashing

Hashing (introduction to) is a DSA topic. In plain words you use it for marks stored somehow in a viva board. Don’t start with a slogan — start with that picture.

Smallest example: array vs list vs hash — one line each. Type it, run it, and say what you see. If you can do that from memory, you know Hashing (introduction to).

From the example next to this theory: Introduction to Hashing — hash maps give average O(1) insert/lookup — dict in Python.

Trap — reciting names with no cost. Fix that before you talk about advanced DSA.

Viva — what is Hashing (introduction to)? Then show array vs list vs hash — one line each. Then name the trap.

Exam tip

What is Hashing (introduction to)? Show this: array vs list vs hash — one line each. Trap: reciting names with no cost.

Example

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.

Short notes

DefHashing (introduction to) — marks stored somehow in a viva board.
Rulearray vs list vs hash — one line each
Trapreciting names with no cost
Usea viva board

DSA · Theory

Introduction to Hashing

← All stacks

Theory

214/810

Introduction to Hashing

Hashing (introduction to) is a DSA topic. In plain words you use it for marks stored somehow in a viva board. Don’t start with a slogan — start with that picture.

Smallest example: array vs list vs hash — one line each. Type it, run it, and say what you see. If you can do that from memory, you know Hashing (introduction to).

From the example next to this theory: Introduction to Hashing — hash maps give average O(1) insert/lookup — dict in Python.

Trap — reciting names with no cost. Fix that before you talk about advanced DSA.

Viva — what is Hashing (introduction to)? Then show array vs list vs hash — one line each. Then name the trap.

Exam tip

What is Hashing (introduction to)? Show this: array vs list vs hash — one line each. Trap: reciting names with no cost.

Example

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.

Short notes

DefHashing (introduction to) — marks stored somehow in a viva board.
Rulearray vs list vs hash — one line each
Trapreciting names with no cost
Usea viva board

Introduction to Hashing

Example

Short notes

Questions

Introduction to Hashing

Example

Short notes

Questions