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Coin Change Problem - minimum number of coins required to make change

Python/Codinghard0.2 min read

**DP:** `dp[i]` = min coins for amount i. `dp[0]=0`; for each coin c: `dp[i]=min(dp[i], 1+dp[i-c])`. O(amount·coins). **Greedy:** Only for canonical systems (US). **Why:** Classic DP; optimization. **Edge:** amount 0; no solution....

🤖 Analyze Your Answer
Frequency
Low
Asked at 1 company
Category
179
questions in Python/Coding
Difficulty Split
127E|24M|28H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Walmart
Interview Pro Tip

Pro-Move: Know when greedy works. Red Flag: Greedy for non-canonical denominations.

Key Concepts Tested
optimization

Why This Question Matters

This hard-level Python/Coding question appears frequently in data engineering interviews at companies like Walmart. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (optimization) will help you answer variations of this question confidently.

How to Approach This

This is a senior-level question that tests architectural thinking. Lead with the high-level design, then drill into specifics. Discuss trade-offs explicitly - there is rarely one correct answer. Show awareness of scale, fault tolerance, and operational complexity.

Expert Answer
35 words

DP: dp[i] = min coins for amount i. dp[0]=0; for each coin c: dp[i]=min(dp[i], 1+dp[i-c]). O(amount·coins). Greedy: Only for canonical systems (US). Why: Classic DP; optimization. Edge: amount 0; no solution. Production: Memoization for recursion.

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According to DataEngPrep.tech, this is one of the most frequently asked Python/Coding interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.

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