557. Reverse Words in a String III

ReverseWords.cs

public class Solution {
  public string ReverseWords(string s) {
    var chars = s.ToCharArray();
    
    void Reverse(char[] word, int left, int right){
      for(; left < right; ++left, --right)
        (word[left], word[right]) = (word[right], word[left]);
    }
    
    int left = 0, right = 0;
    while(right < chars.Length){
      if(chars[right] != ' ') {
        right++;
        continue;
      }
      Reverse(chars, left, right - 1);
      ++right;
      left = right;
    }
    Reverse(chars, left, right - 1);
    
    return new string(chars);
  }
}