Reverse a String

Longest Common Prefix

Merge Intervals

Return a string with every character in reverse order without changing characters.

Return a new string containing the characters of `s` in reverse order. Preserve spaces, punctuation, casing, and repeated characters exactly.

**Input / output**
- Input: `s: string`
- Output: reversed string

**Examples**
1. `"hello"` returns `"olleh"`.
2. `"Hello, World!"` returns `"!dlroW ,olleH"`.

**Constraints**
- `0 <= s.length <= 100,000`
- Treat the input as a sequence of characters; do not trim or normalize it.

**Follow-up**
How would the solution change if the input were a mutable character array that must be reversed in place?

- The task is to reverse a given string `s`.
- We cannot use built-in reverse functions or slicing, so we’ll use a two-pointer approach to reverse the string by swapping characters from each end.

Understanding the Problem

- Set up two pointers: `left` starting at the beginning of the string (0) and `right` starting at the end (length - 1).
- These pointers will move towards each other, swapping characters until they meet in the middle.

Initialize Two Pointers

- Inside a loop, swap the characters at `left` and `right` by storing one in a temporary variable.
- After each swap, increment `left` and decrement `right` to move towards the center of the string.

Swap Characters Using a Third Variable

- Handle edge cases, including:
  - Empty strings, which should return an empty string.
  - Single-character strings, which should return the string itself.
  - Strings with spaces or special characters, which should be reversed as normal.