Freight trains

#include <bits/stdc++.h>

#define REP(i, a, b) for (int i = a; i < b; i++)

// Type Aliases for 1D and 2D vectors with initialization
#define vll(n, val) vector<long long>(n, val) // 1D vector of long longs with size n, initialized to val
#define ll long long
#define vvi(n, m, val) vector<vector<int>>(n, vector<int>(m, val))              // 2D vector of ints (n x m), initialized to val
#define vvll(n, m, val) vector<vector<long long>>(n, vector<long long>(m, val)) // 2D vector of long longs (n x m), initialized to val

using namespace std;

bool min_lexi_result_compare(const string &s, const string &t);

void print_vector(vector<int> &x)
{
    for (int v : x)
    {
        cout << v << " ";
    }
    cout << "\n";
}

void print_matrix(vector<vector<int>> &matrix)
{
    cout << "\n"
         << "----------------" << "\n";
    for (vector<int> row : matrix)
    {
        print_vector(row);
    }
    cout << "\n"
         << "----------------" << "\n";
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

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

    sort(ids.begin(), ids.end(), min_lexi_result_compare);

    for (string c : ids)
    {
        cout << c;
    }
    cout << endl;
}

bool min_lexi_result_compare(const string &s, const string &t)
{
    size_t i = 0, j = 0;
    size_t len_s = s.length(), len_t = t.length();
    size_t total_len = len_s + len_t;
    while (i + j < total_len)
    {
        char c1 = (i < len_s) ? s[i] : t[i - len_s];
        char c2 = (j < len_t) ? t[j] : s[j - len_t];
        if (c1 != c2)
            return c1 < c2;
        if (i < len_s)
            ++i;
        else
            ++j;
    }
    return false; // s + t == t + s, which is impossible since s != t
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: WRONG ANSWER

Test 28

Verdict: WRONG ANSWER

Test 29

Verdict: WRONG ANSWER

Test 30

Verdict: ACCEPTED

Test 31

Verdict: WRONG ANSWER

Test 32

Verdict: WRONG ANSWER

Test 33

Verdict: WRONG ANSWER

Test 34

Verdict: WRONG ANSWER

Test 35

Verdict: WRONG ANSWER

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: WRONG ANSWER

Test 38

Verdict: WRONG ANSWER

Test 39

Verdict: WRONG ANSWER

Test 40

Verdict: WRONG ANSWER

Test 41

Verdict: WRONG ANSWER

Test 42

Verdict: WRONG ANSWER

Test 43

Verdict: WRONG ANSWER

Test 44

Verdict: WRONG ANSWER

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: WRONG ANSWER

Test 47

Verdict: WRONG ANSWER

Test 48

Verdict: WRONG ANSWER

Test 49

Verdict: WRONG ANSWER

Test 50

Verdict: WRONG ANSWER

Test 51

Verdict: WRONG ANSWER

Test 52

Verdict: WRONG ANSWER

Test 53

Verdict: WRONG ANSWER

Test 54

Verdict: WRONG ANSWER

Test 55

Verdict: WRONG ANSWER

Test 56

Verdict: WRONG ANSWER

Test 57

Verdict: WRONG ANSWER

Test 58

Verdict: WRONG ANSWER

Test 59

Verdict: WRONG ANSWER

Test 60

Verdict: WRONG ANSWER

Test 61

Verdict: WRONG ANSWER

Test 62

Verdict: TIME LIMIT EXCEEDED

Test 63

Verdict: TIME LIMIT EXCEEDED

Test 64

Verdict: TIME LIMIT EXCEEDED

Test 65

Verdict: TIME LIMIT EXCEEDED

Test 66

Verdict: TIME LIMIT EXCEEDED

Test 67

Verdict: TIME LIMIT EXCEEDED

Test 68

Verdict: TIME LIMIT EXCEEDED

Test 69

Verdict: TIME LIMIT EXCEEDED

Test 70

Verdict: TIME LIMIT EXCEEDED

Test 71

Verdict: TIME LIMIT EXCEEDED