# [LeetCode 179] Largest Number

### Question

Given a list of non negative integers, arrange them such that they form the largest number.

For example, given `[3, 30, 34, 5, 9]`, the largest formed number is `9534330`.

Note: The result may be very large, so you need to return a string instead of an integer.

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

### Analysis

Please refer to [[ItInt5] Numbers Concatenation Max (Largest Number)(/blog/2014/08/17/Numbers-Concatenation-Max/).

### Solution

Note that we can not override Comparator(Integer). So we must first convert int to string then sort.

### Code

``````public class Solution {

// this code should pass
public String largestNumber(int[] num) {
if (num == null || num.length == 0) {
return "0";
}
String[] strs = new String[num.length];
for (int i = 0; i < num.length; i++) {
strs[i] = String.valueOf(num[i]);
}
Arrays.sort(strs, new LargerComparator());

String res = "";
for (String str : strs) {
res = res + str;
}
return res;
}

class LargerComparator implements Comparator<String> {

public int compare(String a, String b) {
String first = a + b;
String second = b + a;
return second.compareTo(first);
}
}
}
``````