LeeCode 386. 字典序排数

1. LeetCode386题目链接链接

https://leetcode-cn.com/problems/lexicographical-numbers/

2. 结题思路

 

public class MyClass {
    public static void main(String[] args) {
        System.out.println(System.currentTimeMillis());
        System.out.println(new MyClass().lexicalOrder( 5000000));
    }

    public List<Integer> lexicalOrder(int n) {
        List<String> list = new ArrayList<>();
        for (int i = 1;i <= n;i++) {
            StringBuilder builder = new StringBuilder();
            builder.append(i);
            list.add(builder.toString());
        }

        Collections.sort(list);

        List<Integer> answer = new ArrayList<>();
        for (String s : list) {
            answer.add(Integer.parseInt(s));
        }
        System.out.println(System.currentTimeMillis());
        return answer;
    }
}

3. 结果