将数字转成字符串,然后对字符串按指定规则排序

指定规则:a+b>b+a,则a排在b前面

class Solution {
public:
    static bool cmp(string a, string b){
        return a+b > b+a;
    }
    string solve(vector<int>& nums) {
        // write code here
        vector<string> s;
        for(int i=0; i<nums.size(); ++i){
            s.push_back(to_string(nums[i]));
        }
        sort(s.begin(), s.end(), cmp);
        if(s[0] == "0") return "0";
        string res = "";
        for(int i=0; i<nums.size(); ++i)
            res += s[i];
        return res;
    }
};