用sort()排序的方法

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<string> a(n);
    for(int i = 0; i < n; i++) {
        cin >> a[i];
    }

    sort(a.begin(), a.end(), [](const string &x, const string &y) {
        return x + y > y + x;
    });

    string ans;
    for (auto &s : a) ans += s;

    if (ans[0] == '0') cout << "0";
    else cout << ans;

    return 0;
}