344. Reverse String

🟩 Easy

Question

Write a function that reverses a string. The input string is given as an array of characters char[].

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

You may assume all the characters consist of printable ascii characters.

Example 1:

Input: ["h","e","l","l","o"]
Output: ["o","l","l","e","h"]

Example 2:

Input: ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]

Code

def reverseString(self, s: List[str]) -> None:
    i, j = 0, len(s)-1    # Two pointers
    
    while(i<j):
        s[i],s[j] = s[j],s[i]
        i += 1
        j -= 1