leetcode 179 Largest Number

class Solution {
public:
    static bool cmp(string& a, string& b) {
        string ta, tb;
        ta = a + b;
        tb = b + a;
        return ta > tb;
    }
    string largestNumber(vector<int>& nums) {
        vector<string> snums;
        for(int i = 0; i < nums.size(); i++) {
            string nts;
            if(nums[i] == 0) nts += ‘0‘;
            while(nums[i]) {
                nts += (nums[i] % 10) + ‘0‘;
                nums[i] /= 10;
            }
            reverse(nts.begin(), nts.end());
            snums.push_back(nts);
        }
        sort(snums.begin(), snums.end(), cmp);
        string ans;
        int flag = 0;
        for(int i = 0; i < snums.size(); i++) {
            if(snums[i][0] != ‘0‘) flag = 1;
            if(snums[i][0] == ‘0‘ && !flag) continue;
            ans += snums[i];
        }
        if(ans.size() < 1) ans = "0";
        return ans;
    }
};