1public class Solution {
2    public static void reverseWords(String s) {
3        char[] arr = s.toCharArray();
4        int n = arr.length;
5        int start = 0;
6
7        for (int end = 0; end < n; end++) {
8            if (arr[end] == ' ' || end == n - 1) {
9                reverse(arr, start, (end == n - 1) ? end : end - 1);
10                start = end + 1;
11            }
12        }
13        System.out.println(new String(arr));
14    }
15
16    private static void reverse(char[] arr, int start, int end) {
17        while (start < end) {
18            char temp = arr[start];
19            arr[start] = arr[end];
20            arr[end] = temp;
21            start++;
22            end--;
23        }
24    }
25
26    public static void main(String[] args) {
27        String s = "Let's take LeetCode contest";
28        reverseWords(s);
29    }
30}

1using System;
2
public class Solution {
    public static void ReverseWords(string s) {
        char[] arr = s.ToCharArray();
        int start = 0;

        for (int end = 0; end <= arr.Length; end++) {
            if (end == arr.Length || arr[end] == ' ') {
                Reverse(arr, start, end - 1);
                start = end + 1;
            }
        }
        Console.WriteLine(new String(arr));
    }

    private static void Reverse(char[] arr, int start, int end) {
        while (start < end) {
            char temp = arr[start];
            arr[start] = arr[end];
            arr[end] = temp;
            start++;
            end--;
        }
    }

    public static void Main() {
        string s = "Let's take LeetCode contest";
        ReverseWords(s);
    }
}