Solution: Replace Words

Let's solve the Replace Words problem using the Trie pattern.


In this problem, we are considering the words that are composed of a prefixA prefix is a formative element (the smallest meaningful constituent of a linguistic expression) used at the very beginning of a word. For example, ‘un’, ‘dis’, ‘anti’, etc. and a postfixA postfix is a formative element used at the end of a word.. For example, if we append a postfix “happy” to a prefix “un”, it forms the word “unhappy”. Similarly, “disagree” is formed from a prefix, “dis” followed by a postfix, “agree”.

You’re given a dictionary, dictionary, consisting of prefixes, and a sentence, sentence, which has words separated by spaces only. Your task is to replace the postfix in sentence with their prefixes given in dictionary (if found) and return the modified sentence.

A couple of points to keep in mind:

  • If a postfix in the sentence matches more than one prefix in the dictionary, replace it with the prefix that has the shortest length. For example, if we have the sentence “iphone is amazing”, and the dictionary {“i”, “ip”, “hone”}, then the word “iphone” has two prefixes in the dictionary “i” and “ip”, but we will replace it with the one that is shorter among the two, that is, “i”.

  • If there is no root word against any word in the sentence, leave it unchanged.


  • 11 \leq dictionary.length 1000\leq 1000
  • 11 \leq dictionary[i].length 100\leq 100
  • dictionary[i] consists of only lowercase letters.
  • 11 \leq sentence.length 103\leq 10^3
  • The number of words in sentence is in the range [1,100][1, 100].
  • The length of each word in sentence is in the range [1,100][1, 100].
  • Two consecutive words in sentence should be separated by exactly one space.
  • All words in sentence are lowercase.
  • For a word in sentence, the length of a prefix can be [1,100][1, 100], and the length of a postfix can be [0,100][0, 100].

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