Ruudukko

#include <bits/stdc++.h>
using namespace std;

const int mx = 501;
string in[mx][mx];
string dp[mx][mx];
int n;

string f(int i, int j){
  if (i == n && j == n) 
    return in[i][j];
  if (dp[i][j] != "") 
    return dp[i][j];

  string ans;
  if (i == n) 
    ans = in[i][j] + f(i, j + 1);
  else if (j == n) 
    ans = in[i][j] + f(i + 1, j);
  else 
    ans = in[i][j] + min(f(i, j + 1), f(i + 1, j));       
  dp[i][j] = ans;

  return ans;
}


int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  cin >> n;
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= n; ++j) {
      char c;
      cin >> c;

      in[i][j] = string(1, c);
    }
  }

  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= n; ++j) {
      dp[i][j] = "";
    }
  }

  string ans = f(1, 1);
  cout << ans << '\n';
}

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: RUNTIME ERROR

Test 12

Group: 3

Verdict: RUNTIME ERROR

Test 13

Group: 3

Verdict: RUNTIME ERROR

Test 14

Group: 3

Verdict: RUNTIME ERROR

Test 15

Group: 3

Verdict: RUNTIME ERROR