# Leetcode Reverse-Words-In-a-String

#### 2022-07-12 09:10

> ##### Algorithms:
>
> #algorithm #two_pointers
>
> ##### Data structures:
>
> #DS #string
>
> ##### Difficulty:
>
> #coding_problem #difficulty_easy
>
> ##### Additional tags:
>
> #leetcode
>
> ##### Revisions:
>
> N/A

##### Related topics:

##### Links:

- [Link to problem](https://leetcode.com/problems/reverse-words-in-a-string-iii/)

---

### Problem

Given a string `s`, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

#### Examples

**Example 1:**

**Input:** s = "Let's take LeetCode contest"
**Output:** "s'teL ekat edoCteeL tsetnoc"

**Example 2:**

**Input:** s = "God Ding"
**Output:** "doG gniD"

#### Constraints

- `1 <= s.length <= 5 * 104`
- `s` contains printable **ASCII** characters.
- `s` does not contain any leading or trailing spaces.
- There is **at least one** word in `s`.
- All the words in `s` are separated by a single space.

### Thoughts

> [!summary]
> This is a #two_pointers

very easy and intuitive.

### Solution

```cpp
class Solution {
  void reverse(string &s, int l, int r) {
    if (l >= r) {
      return;
    }
    swap(s[l++], s[r--]);
    reverse(s, l, r);
  }

public:
  string reverseWords(string s) {
    int slow = 0, fast;
    for (int i = 0; i < s.size(); i++) {
      if (s[i] == ' ') {
        fast = i - 1;
        reverse(s, slow, fast);
        slow = i + 1;
      }
    }
    reverse(s, slow, s.size() - 1);
    return s;
  }
};
```