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OJ notes/pages/Leetcode Reverse-Words-In-a-String.md

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+# 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:
+```expander
+tag:#two_pointers
+```
+ 
+ 
+
+##### 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;
+  }
+};
+```