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];
    }

    set<pair<int, int>> st;

    st.insert({0, 0});

    string ans;

    while (!st.empty()) {
        char best = 'Z';

        for (auto [y, x] : st) {
            best = min(best, mp[y][x]);
        }

        ans += best;

        set<pair<int, int>> nw;

        for (auto [y, x] : st) {
            if (mp[y][x] == best) {
                if (y + 1 < n) {
                    nw.insert({y + 1, x});
                }
                if (x + 1 < n) {
                    nw.insert({y, x + 1});
                }
            }
        }

        st = nw;
    }

    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: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED