How do you compute the fewest coins to make an amount?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
dp[x] is 1 plus the min of dp[x-coin] over coins that fit, with dp[0]=0 and others inf.
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[x] is 1 plus
the min of dp[x-coin] over coins that fit, with dp[0]=0 and others inf.
- 2Time is O(amount *
coins) and space is O(amount).
- 3How it works
Greedy is not always correct
- 4if dp[amount] stays inf,
return -1.
- 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[x] is 1 plus the min of dp[x-coin] over coins that fit, with dp[0]=0 and others inf. Time is O(amount * coins) and space is O(amount).