Reverse String

# Reverse String ## Difficulty Easy ## Tags `string`, `two pointers` ## Problem Statement Write a function that reverses a string. The input string is given as an array of characters `s`. You must do this by modifying the input array **in-place** with O(1) extra memory. ## Constraints - 1 ≤ s.length ≤ 10⁵ - `s[i]` is a printable ASCII character. ## Signatures ### Python ```python def reverse_string(s: List[str]) -> None: pass ``` ### Java ```java public class Solution { public void reverse_string(List<String> s) { return null; } } ``` ### Csharp ```csharp public class Solution { public void reverse_string(IList<string> s) { throw new NotImplementedException(); } } ``` ### Cpp ```cpp class Solution { public: void reverse_string(vector<string> s) { } }; ``` ### C ```c void reverse_string(vector<char*> s) { } ``` ### Ruby ```ruby def reverse_string(s) end ``` ### Perl ```perl sub reverse_string { my ($self, @args) = @_; } ``` ### Scala ```scala object Solution { def reverse_string(s: List[String]): Unit = { } } ``` ### Haskell ```haskell reverse_string :: ... -> ... reverse_string args = undefined ``` ### Clojure ```clojure (defn reverse_string [s] ) ``` ### Scheme ```scheme (define (reverse_string s) ) ``` ## Examples ### Example 1 **Input:** ``` s = ["h", "e", "l", "l", "o"] ``` **Output:** ``` ["o", "l", "l", "e", "h"] ``` ### Example 2 **Input:** ``` s = ["H", "a", "n", "n", "a", "h"] ``` **Output:** ``` ["h", "a", "n", "n", "a", "H"] ``` ### Example 3 **Input:** ``` s = ["a"] ``` **Output:** ``` ["a"] ``` ## Hints 1. Use two pointers: one at the start, one at the end. 2. Swap elements at both pointers. 3. Move pointers toward each other until they meet.