179. Largest Number

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.

Solution

public static String largestNumber2(int[] nums) {
if (nums == null || nums.length == 0)
return "";
String[] strings = new String[nums.length];
for (int i = 0; i < nums.length; i++) {
strings[i] = String.valueOf(nums[i]);
}
Comparator<String> comparator = new Comparator<String>() {
@Override
public int compare(String s1, String s2) {
String string1 = s1 + s2;
String string2 = s2 + s1;
return string2.compareTo(string1);
}
};

Arrays.sort(strings, comparator);
if (strings[0].charAt(0) == '0') {
return "0";//for {0, 0}
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < strings.length; i++) {
sb.append(strings[i]);
}
return sb.toString();
}