Your free access ends in 7 days — and you haven’t tried it yet. Watch one algorithm run, start to finish. It takes about two minutes.

Try one problem
0
Problem

Prefix Matching

LeetCode #1268Medium
Autocomplete · walk prefix, collect subtree

Insert a set of words into a trie, then given a query prefix return all stored words that begin with that prefix, as in an autocomplete search.

step 1 / 17
trie of 5 words
d
e
r
t
a
c
g
o
d
•
○ = node · ◎ ringed = end of a word
Brute force · scan every word
▸
1given words[], prefix
2result = []
3for w in words:
4    if w.startsWith(prefix): result.add(w)
5return result
state
  • prefix"car"
  • words5

line 1Autocomplete: list every stored word that begins with the prefix "car". Brute force: keep the words in a flat list and test each one's startsWith — including words that obviously can't match.