c++中map会根据key进行排序

class Solution {
public:
    vector lexicalOrder(int n) {
        map nums;
        vector res;
        for(int i=1;i<=n;++i){
            nums[to_string(i)]=i;
        }
        for(auto iter=nums.begin();iter!=nums.end();iter++){
            res.push_back(iter->second);
        }
        return res;
    }
};
```