void sort (RandomAccessIterator first, RandomAccessIterator last, Compare comp);

http://www.cplusplus.com/reference/algorithm/sort/?kw=sort

原题：华中科技大学考研机试题 3608. 大整数排序

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 105;
string a[N];
int n;

int main() {
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a, a + n, [](string a, string b){
        if (a.size() == b.size()) {
            return a < b;
        }
        return a.size() < b.size();
    });
    for (int i = 0; i < n; i++) {
        cout << a[i] << endl;
    }
    return 0;
}

华中科技大学考研机试题