Question:

You are given a string s. Write a function to reverse the string.

Function Signature:

def reverse_string(s: str) -> str:
    pass

Input:

• A string s consisting of lowercase and/or uppercase letters.

Output:

• A string consisting of letters from s in reverse order.

Example:

assert reverse_string("Hello World") == "dlroW olleH"
assert reverse_string("Racecar") == "racecaR"

Explanation:

To reverse a string, we can use a two-pointer approach. One pointer starts from the beginning of the string and moves forward, while the other pointer starts from the end of the string and moves backward.

1. Initialize an empty string result to store the reversed string.
2. Initialize a variable i to 0, representing the pointer starting from the beginning of the string.
3. Initialize a variable j to the length of the string minus 1, representing the pointer starting from the end of the string.
4. Iterate while i is less than or equal to j:
   • Append the character at index j to the result string.
   • Decrement j by 1.
   • Append the character at index i to the result string.
   • Increment i by 1.
5. If the length of the string is odd, there will be one character left at the middle index. Append this character to the result string.
6. Return the result string as the reversed string.

The time complexity of this solution is O(n), where n is the length of the input string.