# 01.05.2024 [2000. Reverse Prefix of Word]

Reverse `[..ch]` prefix in string #easy

01.05.2024

2000. Reverse Prefix of Word easy
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Problem TLDR

Reverse [..ch] prefix in string #easy

Intuition

First find the position, then reverse the prefix.

Approach

Can you make the code shorter? (Don’t do this in the interview, however, we skipped optimized case of not found index.)

Complexity

• Time complexity:
  O(n)

• Space complexity:
  O(n)

Code

    fun reversePrefix(word: String, ch: Char) = String(
        word.toCharArray().apply { reverse(0, indexOf(ch) + 1) }
    )

    pub fn reverse_prefix(mut word: String, ch: char) -> String {
        let i = word.find(ch).unwrap_or(0) + 1;
        word[..i].chars().rev().chain(word[i..].chars()).collect()
    }