186. Reverse Words in a String II

Given an input string , reverse the string word by word. 


Input:  ["t","h","e"," ","s","k","y"," ","i","s"," ","b","l","u","e"]
Output: ["b","l","u","e"," ","i","s"," ","s","k","y"," ","t","h","e"]


  • A word is defined as a sequence of non-space characters.
  • The input string does not contain leading or trailing spaces.
  • The words are always separated by a single space.

Follow up: Could you do it in-place without allocating extra space?

Rust Solution

struct Solution;

impl Solution {
    fn reverse_words(s: &mut Vec<char>) {
        for word in s.split_mut(|&c| c == ' ') {

fn test() {
    let mut s = vec![
        't', 'h', 'e', ' ', 's', 'k', 'y', ' ', 'i', 's', ' ', 'b', 'l', 'u', 'e',
    let res = vec![
        'b', 'l', 'u', 'e', ' ', 'i', 's', ' ', 's', 'k', 'y', ' ', 't', 'h', 'e',
    Solution::reverse_words(&mut s);
    assert_eq!(s, res);

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