Leetcode 179. Largest Number (Medium) (java)

Tag: Sort

Difficulty: Medium

/*

179. Largest Number (Medium)

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.

*/
public class Solution {
	public String largestNumber(int[] num) {
		if(num == null || num.length == 0) return "";
		String[] s_num = new String[num.length];
		for(int i = 0; i < num.length; i++)
			s_num[i] = String.valueOf(num[i]);
		Comparator<String> comp = new Comparator<String>(){
			public int compare(String str1, String str2){
				String s1 = str1 + str2;
				String s2 = str2 + str1;
				return s2.compareTo(s1);
			}
		};
		Arrays.sort(s_num, comp);
		if(s_num[0].charAt(0) == '0') return "0";
		StringBuilder sb = new StringBuilder();
		for(String s: s_num)
			sb.append(s);
		return sb.toString();
	}
}