Word Break
A medium-tier problem at 48% community acceptance, tagged with Array, Hash Table, String. Reported in interviews at Cleartrip and 30 others.
Word Break shows up across 31 companies, from Salesforce to MongoDB to Walmart Labs, and you'll see it in roughly half the attempts people solve it on their first pass. The problem looks deceptively simple: can you segment a string into words from a dictionary. The trap is that a greedy left-to-right scan fails almost immediately on real inputs, and the naive recursive backtrack will time out without memoization. If you hit this in a live assessment and the recursive logic isn't clicking, StealthCoder solves it invisibly in seconds, leaving you to explain the approach to the interviewer.
Companies that ask "Word Break"
Word Break is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderThe core insight is dynamic programming: build a boolean array where index i tells you whether the substring from 0 to i can be segmented into dictionary words. For each position, you check all prior positions j where substring[j:i] matches a word in the dictionary and position j itself was already valid. The algorithm is O(n squared) time with a hash table lookup per check. Candidates often forget memoization on the recursive path or misunderstand the bottom-up DP transitions, leading to stack overflow or timeout. Trie optimization can reduce the search space further. The difference between an acceptable solution and a rejected one usually comes down to whether you cache results or recompute them. StealthCoder's the hedge if the transition logic doesn't land during the assessment.
Pattern tags
You know the problem.
Make sure you actually pass it.
Word Break recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Word Break interview FAQ
Is Word Break still asked at FAANG?+
Yes. It's reported across at least 10 major companies in the input set, including Salesforce, MongoDB, and Walmart Labs. The 48% acceptance rate suggests it's still a filter question, not a gimme.
What's the main trick that catches people?+
Greedy left-to-right scanning doesn't work. You must recognize this as a DP problem where each position depends on previous valid positions, then check dictionary membership for the substring between them.
How does memoization or Trie relate to the core DP?+
Memoization caches recursive calls to avoid recomputing overlapping subproblems. Trie replaces hash table lookups and lets you early-exit on invalid character prefixes, both optimizing the same O(n squared) DP structure.
Can I solve this without DP?+
Technically yes, with pure backtracking and memoization. But you're still trading time for space and building a memo table that mirrors DP logic. DP is cleaner and avoids recursion depth issues.
How hard is Word Break compared to other medium problems?+
It's on the harder end of medium. The 48% acceptance rate is below average, meaning more candidates struggle than nail it. The DP transition isn't intuitive until you've seen it.
Want the actual problem statement? View "Word Break" on LeetCode →