Reverse Words in a String LeetCode Programming Solutions | LeetCode Problem Solutions in C++, Java, & Python [💯Correct]

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Hello Programmers/Coders, Today we are going to share solutions to the Programming problems of LeetCode Solutions in C++, Java, & Python. At Each Problem with Successful submission with all Test Cases Passed, you will get a score or marks and LeetCode Coins. And after solving maximum problems, you will be getting stars. This will highlight your profile to the recruiters.

In this post, you will find the solution for the Reverse Words in a String in C++, Java & Python-LeetCode problem. We are providing the correct and tested solutions to coding problems present on LeetCode. If you are not able to solve any problem, then you can take help from our Blog/website.

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Link for the ProblemReverse Words in a String– LeetCode Problem

Reverse Words in a String– LeetCode Problem

Problem:

Given an input string s, reverse the order of the words.

word is defined as a sequence of non-space characters. The words in s will be separated by at least one space.

Return a string of the words in reverse order concatenated by a single space.

Note that s may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra spaces.

Example 1:

Input: s = "the sky is blue"
Output: "blue is sky the"

Example 2:

Input: s = "  hello world  "
Output: "world hello"
Explanation: Your reversed string should not contain leading or trailing spaces.

Example 3:

Input: s = "a good   example"
Output: "example good a"
Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.

Constraints:

  • 1 <= s.length <= 104
  • s contains English letters (upper-case and lower-case), digits, and spaces ' '.
  • There is at least one word in s.
Reverse Words in a String– LeetCode Solutions
Reverse Words in a String Solution in C++:
class Solution {
 public:
  string reverseWords(string s) {
    reverse(begin(s), end(s));          // reverse the whole string
    reverseWords(s, s.length());        // reverse each word
    return cleanSpaces(s, s.length());  // clean up spaces
  }

 private:
  void reverseWords(string& s, int n) {
    int i = 0;
    int j = 0;

    while (i < n) {
      while (i < j || i < n && s[i] == ' ')  // skip spaces
        ++i;
      while (j < i || j < n && s[j] != ' ')  // skip non spaces
        ++j;
      reverse(begin(s) + i, begin(s) + j);  // reverse the word
    }
  }

  // trim leading, trailing, and middle spaces
  string cleanSpaces(string& s, int n) {
    int i = 0;
    int j = 0;

    while (j < n) {
      while (j < n && s[j] == ' ')  // skip spaces
        ++j;
      while (j < n && s[j] != ' ')  // keep non spaces
        s[i++] = s[j++];
      while (j < n && s[j] == ' ')  // skip spaces
        ++j;
      if (j < n)  // keep only one space
        s[i++] = ' ';
    }

    return s.substr(0, i);
  }
};
Reverse Words in a String Solution in Java:
class Solution {
  public String reverseWords(String s) {
    StringBuilder sb = new StringBuilder(s).reverse(); // reverse the whole string
    reverseWords(sb, sb.length());                     // reverse each word
    return cleanSpaces(sb, sb.length());               // clean up spaces
  }

  private void reverseWords(StringBuilder sb, int n) {
    int i = 0;
    int j = 0;

    while (i < n) {
      while (i < j || i < n && sb.charAt(i) == ' ') // skip spaces
        ++i;
      while (j < i || j < n && sb.charAt(j) != ' ') // skip non spaces
        ++j;
      reverse(sb, i, j - 1); // reverse the word
    }
  }

  // trim leading, trailing, and middle spaces
  private String cleanSpaces(StringBuilder sb, int n) {
    int i = 0;
    int j = 0;

    while (j < n) {
      while (j < n && sb.charAt(j) == ' ') // skip spaces
        ++j;
      while (j < n && sb.charAt(j) != ' ') // keep non spaces
        sb.setCharAt(i++, sb.charAt(j++));
      while (j < n && sb.charAt(j) == ' ') // skip spaces
        ++j;
      if (j < n) // keep only one space
        sb.setCharAt(i++, ' ');
    }

    return sb.substring(0, i).toString();
  }

  private void reverse(StringBuilder sb, int l, int r) {
    while (l < r) {
      final char temp = sb.charAt(l);
      sb.setCharAt(l++, sb.charAt(r));
      sb.setCharAt(r--, temp);
    }
  }
}
Reverse Words in a String Solution in Python:
class Solution:
  def reverseWords(self, s: str) -> str:
    return ' '.join(reversed(s.split()))

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