Moderate Sliding Window Question 91 of 224

How do you find all start indices of anagrams of p inside s?

DSA interview set · Speak this in 60–90 seconds · Faridabad & Delhi NCR

PICTURE THIS: HOW TO EXPLAIN IT

IdeaSliding Window
HowWhat happens inside
Why they askShows real use

Simple meaning

Maintain a window of length p with character counts

1

WHY — Sliding Window instead of guessing?

Why interviewers care about Sliding Window:

This is a process

question about Sliding Window.

Panels listen for order,

trade-offs, and what you would actually do on a DSA project - not buzzwords.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

2

STEPS — What happens step by step?

Before you speak the answer, walk the interviewer through these steps:

  1. 1
    Maintain a window of

    length p with character counts

  2. 2
    slide by adding s[i]

    and removing s[i-len(p)], and record i-len(p)+1 when counts match.

  3. 3
    Time is O(|s| +

    |p|) with O(1) alphabet space.

  4. 4
    Comparing 26 counters each

    step is still O(n) given a fixed alphabet.

  5. 5
    Common mistake

    What juniors usually get wrong.

  6. 6
    Close

    When you pick this over the alternative.

3

EXAMPLE — See it in action

Here's a short line you can speak, broken into clear beats:

Say this line
“Time is O(|s| + |p|) with O(1) alphabet space.”
Break into beats
TimeisOspwith
Speaking order
2987408337471632900

Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

Key takeaway

Maintain a window of length p with character counts slide by adding s[i] and removing s[i-len(p)], and record i-len(p)+1 when counts match.

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