leetcode 386. Lexicographical Numbers 前K个字典序数组 + 字典序排序

Given an integer n, return 1 - n in lexicographical order.

For example, given 13, return: [1,10,11,12,13,2,3,4,5,6,7,8,9].

Please optimize your algorithm to use less time and space. The input size may be as large as 5,000,000.

这道题就是做一个拓扑排序，可以使用排序来做，但是这个肯定会超时，最好使用循环来做，这是网上看的一个答案

建议和这一道题leetcode 440. K-th Smallest in Lexicographical Order 第k个字典序的数字 一起学习

这道题最直接跌方法就是直接比较排序，下面的这种做法我没想出来这么做，很棒的想法

代码如下：

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;



bool cmp(int a, int b)
{
    return to_string(a) < to_string(b);
}

class Solution 
{
public:
    vector<int> lexicalOrder(int n)
    {
        vector<int> res(n,0);
        int cur = 1;
        for (int i = 0; i < n; i++)
        {
            res[i] = cur;
            if (cur * 10 <= n)
                cur *= 10;
            else
            {
                if (cur >= n)
                    cur /= 10;
                cur += 1;
                while (cur % 10 == 0)
                    cur /= 10;
            }
        }
        return res;
    }

    vector<int> lexicalOrderBySort(int n) 
    {
        vector<int> res;
        for (int i = 1; i <= n; i++)
            res.push_back(i);
        sort(res.begin(), res.end(),cmp);
        return res;
    }
};