Ruudukko

#include <iostream>
#include <string>
#include <cmath>
#include <cstdio>
#include <algorithm>

using namespace std;

typedef int ll;

ll n;
ll t;

ll go(char * ruudut, ll i, ll sum, bool print) {
	// cout << "i: " << i << " print: " << print << endl;
	if (i == t - 1) {
		// if (print) cout << ruudut[i] << endl;
		return sum;
	}
	if (i % n == n - 1) {
		if (print) cout << ruudut[i + n];
		return go(ruudut, i + n, sum, print) + ruudut[i];
	}
	if (i / n == n - 1) {
		if (print) cout << ruudut[i + 1];
		return go(ruudut, i + 1, sum, print) + ruudut[i];
	}
	char down = ruudut[i + n], right = ruudut[i + 1];
	if (down < right) {
		if (print) cout << down;
		return go(ruudut, i + n, sum, print) + ruudut[i];
	}
	if (right < down) {
		if (print) cout << right;
		return go(ruudut, i + 1, sum, print) + ruudut[i];
	}
	ll d = go(ruudut, i+n, 0, false);
	ll r = go(ruudut, i+1, 0, false);
	if (d < r) {
		if (print) cout << down;
		return go(ruudut, i + n, sum, print) + ruudut[i];
	}
	if (print) cout << right;
	return go(ruudut, i + 1, sum, print) + ruudut[i];
}

int main() {

	ios_base::sync_with_stdio(false);

	cin >> n;
	t = n*n;

	char ruudut[t];

	for (ll i = 0; i < t; ++i) {
		static char c;
		do {
			cin >> c;
			// cout << "'" << c << "' ";
		} while (isspace(c));
		ruudut[i] = c;
	}

	cout << ruudut[0];
	go(ruudut, 0, 0, true);
	cout << '\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: TIME LIMIT EXCEEDED

Test 7

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 8

Group: 2

Verdict: WRONG ANSWER

Test 9

Group: 2

Verdict: WRONG ANSWER

Test 10

Group: 2

Verdict: WRONG ANSWER

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