# 179 Largest Number – Medium

### Problem:

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.

### Thoughts:

The trick is to implement a custom comparator then leverage Arrays.sort method. Also, note that if implement Comparator, you cannot use Arrays.sort(int[[], CustomComparator) because int cannot be automatically casted into Integer object in this case.

### Solutions:

``````public class Solution {
public String largestNumber(int[] nums) {
String[] snums = new String[nums.length];
for (int i = 0; i < nums.length; i ++){
snums[i] = "" + nums[i];
}
Arrays.sort(snums, new Comparator<String>(){
public int compare(String a, String b){
String atob = a + b;
String btoa = b + a;
return btoa.compareTo(atob);
}
});
String result = "";
for (int i = 0; i < snums.length; i ++){
result +=snums[i];
} //remove front zeroes
while (result.length() > 1){
if (result.charAt(0) == '0')
result = result.substring(1);
else
break;
}
return result;
}//largestNumber
}
``````
``````public class Solution {
class StrComparator implements Comparator<String> {
@Override
public int compare(String s1, String s2) {
String s1s2 = s1 + "" + s2;
String s2s1 = s2 + "" + s1;
return s1s2.compareTo(s2s1);
}
}
public String largestNumber(int[] nums) {
String[] strs = new String[nums.length];
for (int i = 0; i < nums.length; i ++) {
strs[i] = nums[i] + "";
}
Arrays.sort(strs, new StrComparator());
String result = "";
for (int i = 0; i < strs.length; i ++) {
result = strs[i] + result;
}
if (result.charAt(0) == '0') {
return "0";
}
return result;
}
}
``````