Reverse string prefix

Two Pointers String

89.4% acceptance

Mar 15, 2026

You are given a string s and an integer k. Reverse the first k characters of s and return the resulting string.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn reverse_prefix(s: String, k: i32) -> String {
    let k = k as usize;
    let mut chars: Vec<char> = s.chars().collect();
    chars[..k].reverse();
    chars.into_iter().collect()
  }
}