1-5

public class Solution {
    public String reverseString(char[] s) {
        int i = 0;
        int j = s.length - 1;
        while (i < j) {
            char temp = s[i];
            s[i] = s[j];
            s[j] = temp;
            i++;
            j--;
        }
        return null;
    }
}



public class Solution {
    public String reverseString(char[] s) {
        char[] t = new StringBuilder().append(s).reverse().toString().toCharArray();
        System.arraycopy(t, 0, s, 0, s.length);
        return null;
    }
}