How do you solve the Word Break problem efficiently?
This problem asks if a string can be segmented into words from a dictionary. It tests DP and memoization.
Why Interviewers Ask This
Interviewers ask this to test string segmentation and DP state transitions. They want to see if you can break the string into valid substrings. It demonstrates recursive thinking with memoization.
How to Answer This Question
Explain the DP approach where dp[i] is true if s[0..i] can be segmented. For each i, check all j < i; if dp[j] is true and s[j..i] is in the dictionary, set dp[i] to true. Alternatively, use recursion with memoization. Discuss time complexity based on string length and dictionary size.
Key Points to Cover
- DP state definition
- Substring extraction
- Dictionary lookup
- Base case handling
Sample Answer
I use dynamic programming where dp[i] indicates if the substring s[0..i] can be broken into dictionary words. I initialize dp[0] as true. For each position i from 1 to n, I check all j < i. If dp[j] is true and the subst…
Common Mistakes to Avoid
- Not checking all possible split points
- Incorrect substring indexing
- Forgetting to initialize dp[0]
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