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Bloomberg·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Bloomberg SWE interview with a backtracking/DP problem. Nothing too wild but Word Break II is one of those questions that looks manageable until you start thinking about all the edge cases.

Questions Asked (1)

Q1

Given a string and a dictionary of words, return all possible ways to segment the string into valid dictionary words, where words can be reused.

Algorithms & Data Structures
Author's notes

Classic backtracking with memoization.

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AI HintsAI Generated

Suggested Approach

Use backtracking to explore all possible segmentations, leveraging a trie or hash set for O(1) word lookups. Optimize with memoization to avoid redundant computations on overlapping subproblems, and discuss time/space complexity.

Pro tip: Clarify whether words can be reused (yes) and whether the output should be deduplicated; also mention that memoization can drastically reduce runtime for strings with many repeated prefixes.

1. Clarify requirements and edge cases

Confirm that words can be reused, the dictionary is a set for O(1) lookups, and handle empty string, no valid segmentation, and duplicate words in dictionary.

2. Choose data structures

Use a hash set for the dictionary for O(1) lookups, or a trie for prefix-based pruning. Use a list to collect results and a memo to cache failed or successful segmentations.

3. Design recursive backtracking

Define a function that takes the current index and builds a path. At each step, try all substrings starting at the index; if a substring is in the dictionary, recurse on the next index.

4. Add memoization

Cache results for each starting index to avoid recomputing the same suffix. If a suffix yields no valid segmentations, store an empty list to skip future exploration.

5. Analyze complexity and test

Discuss time complexity: O(2^n) worst-case without memoization, but with memoization it's O(n * L) where L is max word length. Test with examples like 'catsanddog' and edge cases.

Key Points to Mention

  • Backtracking with recursion to explore all segmentations
  • Using a hash set or trie for O(1) or O(L) word lookups
  • Memoization to cache results per index and avoid redundant work
  • Time and space complexity analysis, including worst-case exponential without memoization
  • Handling edge cases: empty string, no valid segmentation, words reused
  • Potential optimization: pruning with maximum word length or trie traversal

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.