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This approach involves splitting the original string into individual words using space as a delimiter, reversing the list of words, and then joining them back together with a single space.
Time Complexity: O(N), where N is the length of the string, as we process each character once.
Space Complexity: O(N), additional space for intermediate and result storage.
1def reverseWords(s: str) -> str:
2 words = s.split()
3 return ' '.join(reversed(words))
4
5input_str = " hello world "
6output_str = reverseWords(input_str)
7print(output_str)The Python solution is concise with split() and reversed() to obtain reversed words and join them together with a space.
This optimized approach manipulates the string in place by using a character array. We'll first reverse the entire string, and then reverse each word to return them to their correct order.
Time Complexity: O(N), where N is the number of characters in the string.
Space Complexity: O(1), as the operation is done in-place without extra space.
1using System.Text;
public class Solution {
public static string ReverseWords(string s) {
char[] chars = s.Trim().ToCharArray();
int n = chars.Length;
void Reverse(int start, int end) {
while (start < end) {
char temp = chars[start];
chars[start] = chars[end];
chars[end] = temp;
start++;
end--;
}
}
Reverse(0, n - 1);
int rightIndex = 0;
for (int i = 0; i < n; ++i) {
if (chars[i] == ' ') continue;
int start = i;
while (i < n && chars[i] != ' ') i++;
Reverse(start, i - 1);
while (start < i) chars[rightIndex++] = chars[start++];
if (rightIndex < n) chars[rightIndex++] = ' ';
}
return new String(chars, 0, rightIndex == 0 ? 0 : rightIndex - 1);
}
public static void Main() {
string input = " hello world ";
string output = ReverseWords(input);
Console.WriteLine(output);
}
}The C# solution includes reversing the whole character array initially, and then processing each token to be reversed in place before constructing the final string with correct whitespace handling.