Java O(n) Simple Solution that Interviewers Are Looking For

[bzmo96]

Explanation
If you get asked this, you're expected to deal with arrays and do some basic character swapping logic.

Time Complexity
The time complexity is O(n), where n is the number of characters in our string s, since the for loop iterates through n/2 characters.

class Solution {
    public String reverseString(String s) {
        char [] ch = s.toCharArray();
        for (int i = 0; i < ch.length/2; i++) {
           // Swap characters
            char tmp = ch[i];
            ch[i] = ch[ch.length - 1 - i];
            ch[ch.length - 1 - i] = tmp;
        }
        return new String(ch);
    }
}