LeetCode179.java

package problems;

import java.util.Arrays;
import java.util.PriorityQueue;

public class LeetCode179 {
    public String largestNumber(int[] nums) {
        int n = nums.length;
        Integer[] numsArr = new Integer[n];
        for (int i = 0; i < n; i++) {
            numsArr[i] = nums[i];
        }
        Arrays.sort(numsArr, (x, y) -> {
            long sx = 10, sy = 10;
            while (sx <= x) {
                sx *= 10;
            }
            while (sy <= y) {
                sy *= 10;
            }
            return (int) (-sy * x - y + sx * y + x);
        });

        if (numsArr[0] == 0) {
            return "0";
        }
        StringBuilder ret = new StringBuilder();
        for (int num : numsArr) {
            ret.append(num);
        }
        return ret.toString();
    }

    public String largestNumber1(int[] nums) {
        PriorityQueue<String> heap = new PriorityQueue<>((x, y) -> (y + x).compareTo(x + y));
        for(int x: nums) heap.offer(String.valueOf(x));
        String res = "";
        while(heap.size() > 0) res += heap.poll();
        if(res.charAt(0) == '0') return "0";
        return res;
    }
}