class Solution {

    public String largestNumber(int[] nums) {

        for(int i = 0; i < nums.length; i++){

            for(int j = 0; j < nums.length - i - 1; j++){

                String s1 = nums[j] + "" + nums[j + 1];

                String s2 = nums[j + 1] + "" + nums[j];

                if(s1.compareTo(s2) < 0){

                    int temp = nums[j];

                    nums[j] = nums[j + 1];

                    nums[j + 1] = temp;

                }

            }

        }

        String res = "";

        for(int i = 0; i < nums.length; i++){

            res += nums[i];

        }

        if(res.charAt(0) == '0'){

            return "0";

        }

        return res;

    }

}

public class Solution {

     public String largestNumber(int[] num) {

        if(num == null || num.length == 0)

            return "";

        // Convert int array to String array, so we can sort later on

        String[] s_num = new String[num.length];

        for(int i = 0; i < num.length; i++)

            s_num[i] = String.valueOf(num[i]);

        // Comparator to decide which string should come first in concatenation

        Comparator<String> comp = new Comparator<String>(){

            @Override

            public int compare(String str1, String str2){

                String s1 = str1 + str2;

            String s2 = str2 + str1;

            return s2.compareTo(s1); // reverse order here, so we can do append() later

            }

            };

        Arrays.sort(s_num, comp);

                // An extreme edge case by lc, say you have only a bunch of 0 in your int array

                if(s_num[0].charAt(0) == '0')

                    return "0";

        StringBuilder sb = new StringBuilder();

        for(String s: s_num)

                sb.append(s);

        return sb.toString();

    }

}

class Solution {

    public String convert(String s, int numRows) {

     char[] c = s.toCharArray();

        int len = c.length;

        StringBuilder[] sb = new StringBuilder[numRows];

        for(int i = 0; i < numRows; i++){

            sb[i] = new StringBuilder();

        }

        int idx = 0;

        while(idx < len){

            for(int i = 0; i < numRows && idx < len; i++){

                sb[i].append(c[idx++]);

            }

            for(int i = numRows - 2; i >= 1 && idx < len; i--){

                sb[i].append(c[idx++]);

            }

        }

        for(int i = 1; i < sb.length; i++){

            sb[0].append(sb[i]);

        }

        return sb[0].toString();

    }

}

class Solution {

    public String convertToTitle(int n) {

        StringBuilder sb = new StringBuilder();

        int reminder = 0;

        while(n > 0){

            reminder = (n - 1) % 26;

            sb.insert(0, (char)(reminder + 'A'));

            n = (n - reminder) / 26;

        }

        return sb.toString();

    }

}