Ruudukko

import java.util.Arrays;
 
 
public class Ruudukkokulkija {
 
	static int n;
	static char[][] r;
	
	public static void main(String[] args) {
		IO io = new IO();
		
		n = io.nextInt();
		
		r = new char[n][];
		
		for (int i = 0; i < n; i++) {
			r[i] = io.next().toCharArray();
		}
		
		io.println(mene(0, 0, ""));
		
		io.close();
	}
 
	static String mene(int x, int y, String a, String... vsz) {
		
		a += r[y][x];
		
		if (vsz.length > 0) {
			for (String vz : vsz) {
				String nvz = vz;
				while (nvz.length() < a.length()) nvz += 'Z';
				if (nvz.compareTo(a) < 0) return nvz;
			}
		}
		
		if (x+1 == n && y+1 == n) {
			return a;
		}
		
		if (x+1 == n) {
			y++;
			return mene(x, y, a);
		}
		
		if (y+1 == n) {
			x++;
			return mene(x, y, a);
		}
		
		char az = r[y][x+1];
		char bz = r[y+1][x];
		if (az < bz) {
			return mene(x+1, y, a);
		} else if (az > bz) {
			return mene(x, y+1, a);
		} else {
			String asz = mene(x+1, y, a);
			String[] nvsz = new String[vsz.length+1];
			System.arraycopy(vsz, 0, nvsz, 0, vsz.length);
			nvsz[vsz.length] = asz;
			String bsz = mene(x, y+1, a, nvsz);
			if (asz.compareTo(bsz) < 0) return asz;
			else return bsz;
		}
	}
	
}

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: 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