Ruudukko

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long

using namespace std;

int n;
char chaa[3030][3030];
bool qaq[3030][3030];
set<pair<string,pair<int,int>>> q;

int main() {
	cin.tie(0);
	cout.tie(0);
	ios_base::sync_with_stdio(0);
	cin >> n;
	for(int i=1; i<=n; i++) {
		for(int j=1; j<=n; j++) {
			cin >> chaa[j][i];
		}
	}
	string aaa = "";
	aaa.push_back(chaa[1][1]);
	q.insert(make_pair(aaa, make_pair(1, 1)));
	while((*(q.begin())).second.first!=n||(*(q.begin())).second.second!=n) {
		pair<string, pair<int,int>> up;
		string sa = (*q.begin()).first;
		int xx = (*q.begin()).second.first;
		int yy = (*q.begin()).second.second;
		q.erase(q.begin());
		if(xx+1<=n) {
			string ss = sa;
			ss.push_back(chaa[xx+1][yy]);
			q.insert(make_pair(ss, make_pair(xx+1, yy)));
		}
		if(yy+1<=n) {
			sa.push_back(chaa[xx][yy+1]);
			q.insert(make_pair(sa, make_pair(xx, yy+1)));
		
		}
	}
	cout << (*q.begin()).first;
}

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