DSA · Theory

Hashing and its Applications

Theory

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Hashing and its Applications

Hashing and its Applications 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 Hashing and its Applications.

From the example next to this theory: Hashing and its Applications — 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 Hashing and its Applications? Then show key % size + collision plan. Then name the trap.

Exam tip

What is Hashing and its Applications? Show this: key % size + collision plan. Trap: bad hash → pile-up.

Example

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

Hashing and its Applications — hash maps give average O(1) insert/lookup — dict in Python.

Short notes

DefHashing and its Applications — name → phone in a diary.
Rulekey % size + collision plan
Trapbad hash → pile-up
Usea diary

DSA · Theory

Hashing and its Applications

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Theory

559/810

Hashing and its Applications

Hashing and its Applications 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 Hashing and its Applications.

From the example next to this theory: Hashing and its Applications — 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 Hashing and its Applications? Then show key % size + collision plan. Then name the trap.

Exam tip

What is Hashing and its Applications? Show this: key % size + collision plan. Trap: bad hash → pile-up.

Example

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

Hashing and its Applications — hash maps give average O(1) insert/lookup — dict in Python.

Short notes

DefHashing and its Applications — name → phone in a diary.
Rulekey % size + collision plan
Trapbad hash → pile-up
Usea diary

Hashing and its Applications

Example

Short notes

Questions

Hashing and its Applications

Example

Short notes

Questions