身份证排序问题

#include <bits/stdc++.h>
using namespace std;
int main() {
    int n;
    cin >> n;
    vector<string> a(n);
    for (int i = 0; i < n; ++i) cin >> a[i];
    /* 根据第7~14位进行排序 */
    sort(a.begin(), a.end(), [](string &lhs, string &rhs) {
        string l = lhs.substr(6, 8);
        string r = rhs.substr(6, 8);
        return l > r || (l == r && lhs < rhs);
    });
    for (auto &s: a) cout << s << endl;
    return 0;
}