PLEASE CHECK OJ

public class Solution {
    static int [] p = new int [1010];

    public String longestPalindrome(String s) {
        s = "#" + String.join("#", s.split("")) + "#";
        int n = s.length();

        if(n == 0) return "";

        int maxp = 0, pos = 0, ret = 0;

        for(int i = 0; i < n; ++i) {
            if(i < maxp) p[i] = Math.min(p[2 * pos - i], maxp - i);
            else p[i] = 1;

            while(i - p[i] >= 0 && i + p[i] < n &&
                    s.charAt(i - p[i]) == s.charAt(i + p[i]))
                ++p[i];

            if(p[i] + i - 1 > maxp) {
                maxp = p[i] + i - 1;
                pos = i;
            }

            if(p[i] > p[ret] || (p[i] == p[ret] && s.charAt(i) != '#')) ret = i;
        }

        // System.out.println(ret + " " + p[ret] + " " + s);
        // for(int x : p) System.out.println(x);
        String ans = s.substring(ret - p[ret] + 1, ret + p[ret]);
        // System.out.println(ans + " " + ret + " " + p[ret] + " " + s);
        ans = ans.replace("#", "");
        return ans;
    }
}

public class Solution {
    public int myAtoi(String str) {
        str = str.replaceAll("^ *", "");
        if(str.length() == 0) return 0;
        System.out.println(str);
        boolean negative = false;
        int start = 0, end = -1;
        if(str.charAt(0) == '+' || str.charAt(0) == '-') {
            negative = str.charAt(0) == '-';
            start = 1;
        }
        for(end = start; end < str.length(); ++end)
            if(!Character.isDigit(str.charAt(end))) break;
        str = str.substring(start, end);
        System.out.println(str);

        try {
            if(str.length() == 0) return 0;
            return Integer.parseInt((negative ? "-" : "") + str);
        } catch(Exception e) {
            return negative ? Integer.MIN_VALUE : Integer.MAX_VALUE;
        }
    }
}