How do you compute the edit distance between two strings?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
dp[i][j] is the min of replace, delete, or insert to turn word1[:i] into word2[:j], with a free diagonal copy when characters match.
WHY — DP instead of guessing?
Why interviewers care about DP:
question about DP.
trade-offs, and what you would actually do on a DSA project - not buzzwords.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1dp[i][j] is the min
of replace, delete, or insert to turn word1[:i] into word2[:j], with a free diagonal copy when characters match.
- 2Why it exists
Time and space are O(n*m)
- 3one row rolling is
O(min(n,m)) space.
- 4This is the standard
Levenshtein recurrence to name in interviews.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
dp[i][j] is the min of replace, delete, or insert to turn word1[:i] into word2[:j], with a free diagonal copy when characters match. Time and space are O(n*m)