Stream of Characters

Hard
Concept
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Solution Guide: Stream of Characters

Approach

Build trie over reversed words. Append new letters to stream and scan all suffixes from end against trie in O(maxWordLen) per query.

Complexity Analysis

Time
O(M)
Space
O(total characters)

Pattern

Reverse Trie for Streaming Prefix/Suffix Match

Why It Works

Any matching word suffix appears as a reversed prefix from the newest stream characters, so checking backwards in reverse-trie detects all endings.

Updated Feb 2026