DSA · Theory

Big O Notation in DS

Theory

199/810

Big O Notation in DS

Big O Notation in DS is a DSA topic. In plain words you use it for n vs n² on 10k rows in a viva. Don’t start with a slogan — start with that picture.

Smallest example: best / average / worst + extra memory. Type it, run it, and say what you see. If you can do that from memory, you know Big O Notation in DS.

From the example next to this theory: Big O Notation in DS — big-O describes how work grows with input size — ignore constants.

Trap — saying ‘fast’ with no Big-O. Fix that before you talk about advanced DSA.

Viva — what is Big O Notation in DS? Then show best / average / worst + extra memory. Then name the trap.

Exam tip

What is Big O Notation in DS? Show this: best / average / worst + extra memory. Trap: saying ‘fast’ with no Big-O.

Example

def demo(n):
    # O(1)
    x = n + 1
    # O(n)
    total = sum(range(n))
    # O(n^2)
    pairs = 0
    for i in range(n):
        for j in range(n):
            pairs += 1
    return x, total, pairs

print(demo(3))

Big O Notation in DS — big-O describes how work grows with input size — ignore constants.

Short notes

DefBig O Notation in DS — n vs n² on 10k rows in a viva.
Rulebest / average / worst + extra memory
Trapsaying ‘fast’ with no Big-O
Usea viva

DSA · Theory

Big O Notation in DS

← All stacks

Theory

199/810

Big O Notation in DS

Big O Notation in DS is a DSA topic. In plain words you use it for n vs n² on 10k rows in a viva. Don’t start with a slogan — start with that picture.

Smallest example: best / average / worst + extra memory. Type it, run it, and say what you see. If you can do that from memory, you know Big O Notation in DS.

From the example next to this theory: Big O Notation in DS — big-O describes how work grows with input size — ignore constants.

Trap — saying ‘fast’ with no Big-O. Fix that before you talk about advanced DSA.

Viva — what is Big O Notation in DS? Then show best / average / worst + extra memory. Then name the trap.

Exam tip

What is Big O Notation in DS? Show this: best / average / worst + extra memory. Trap: saying ‘fast’ with no Big-O.

Example

def demo(n):
    # O(1)
    x = n + 1
    # O(n)
    total = sum(range(n))
    # O(n^2)
    pairs = 0
    for i in range(n):
        for j in range(n):
            pairs += 1
    return x, total, pairs

print(demo(3))

Big O Notation in DS — big-O describes how work grows with input size — ignore constants.

Short notes

DefBig O Notation in DS — n vs n² on 10k rows in a viva.
Rulebest / average / worst + extra memory
Trapsaying ‘fast’ with no Big-O
Usea viva

Big O Notation in DS

Example

Short notes

Questions

Big O Notation in DS

Example

Short notes

Questions