Ruudukko

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;

#define M 1000000007

string mp[501];
pair<int, int> from[501][501];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;


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

    from[0][0] = {-1, -1};

    for (int i = 1; i < n; ++i) {
        from[i][0] = {i - 1, 0};
        from[0][i] = {0, i - 1};
    }

    for (int i = 1; i < n; ++i) {
        for (int j = 1; j < n; ++j) {
            string above;
            pair<int, int> pos = {i - 1, j};
            while (pos != make_pair(-1, -1)) {
                above += mp[pos.first][pos.second];
                pos = from[pos.first][pos.second];
            }

            string leftside;
            pos = {i, j - 1};
            while (pos != make_pair(-1, -1)) {
                leftside += mp[pos.first][pos.second];
                pos = from[pos.first][pos.second];
            }
            reverse(above.begin(), above.end());
            reverse(leftside.begin(), leftside.end());

            if (above < leftside) {
                from[i][j] = {i - 1, j};
            } else {
                from[i][j] = {i, j - 1};
            }
        }
    }

    string ans;
    pair<int, int> pos = {n - 1, n - 1};
    while (pos != make_pair(-1, -1)) {
        ans += mp[pos.first][pos.second];
        pos = from[pos.first][pos.second];
    }

    reverse(ans.begin(), ans.end());

    cout << ans << "\n";

    return 0;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 13

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 15

Group: 3

Verdict: TIME LIMIT EXCEEDED