Message Splitting With Paginated Suffixes

What's being tested

Tests string segmentation with variable-length metadata, where each chunk must fit limit including a suffix like <i/n>. The key skill is deriving the minimum feasible page count, then slicing the original message without reordering or dropping characters.

Patterns & templates

• Feasibility check for a candidate n: total payload capacity is $\sum_{i=1}^{n} limit - len("<i/n>")$; require capacity >= len(message).

• Digit-length bucketing avoids repeated string conversion: len(str(i)) is constant over ranges [1,9], [10,99], etc.

• Linear search over page count is often acceptable when message.length is moderate; otherwise optimize with digit buckets, not naive per-page recomputation.

• Impossible-case guard: if any suffix length len("<i/n>") >= limit, that page has no payload capacity, so candidate n is invalid.

• Two-pass construction: first find minimal feasible n, then build chunks by taking limit - suffix.length characters and appending suffix.

• Complexity target: O(L + n) time and O(L + n log n) output space, where L = message.length; avoid quadratic string concatenation.

• Use StringBuilder, list append, or substring indices; repeated result += chunk can degrade to O(L^2) in many languages.

Common pitfalls

Pitfall: Treating suffix length as constant; <9/10> and <10/10> have different widths.

Pitfall: Choosing n = ceil(len(message) / limit) before accounting for suffix overhead, which underestimates page count.

Pitfall: Returning non-minimal valid segmentation when the problem asks for the smallest number of parts.

Practice these

The practice cards below cover the canonical variants — solve all of them and time yourself.