LeetCode link

Intuition

  • Sort the numbers as strings in ascending order, the comparator is (s2 + s1).compareTo(s1 + s2)

solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
class Solution {
    public String largestNumber(int[] nums) {
        if (nums.length < 1) {
            return "";
        }
        String[] strs = new String[nums.length];
        for (int i = 0; i < nums.length; i++) {
            strs[i] = String.valueOf(nums[i]);
        }
        Arrays.sort(strs, new Comparator<String>() {
            public int compare(String s1, String s2) {
                return (s2 + s1).compareTo(s1 + s2);
            }
        });
        String result = "";
        for (String str: strs) {
            result += str;
        }
        return result;
    }
}

problem

WA.

Input:
[0,0]
Output:
“00”
Expected:
“0”

reason

Miss the zero situation.

modification

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
class Solution {
    public String largestNumber(int[] nums) {
        if (nums.length < 1) {
            return "";
        }
        String[] strs = new String[nums.length];
        for (int i = 0; i < nums.length; i++) {
            strs[i] = String.valueOf(nums[i]);
        }
        Arrays.sort(strs, new Comparator<String>() {
            public int compare(String s1, String s2) {
                return (s2 + s1).compareTo(s1 + s2);
            }
        });
        if (strs[0].equals("0")) {
            return "0";
        }
        String result = "";
        for (String str: strs) {
            result += str;
        }
        return result;
    }
}