Chess board tour

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

#define I_2D(row, col, width) ((row) * (width) + (col))
#define PRINT_ARR(arr, n)                                                      \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << arr[i] << " ";                                                   \
    }                                                                          \
    cout << "\n";                                                              \
  } while (0)
#define PRINT_VEC_ARR(v, n)                                                    \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << i << ": ";                                                       \
      for (auto item : v[i]) {                                                 \
        cout << item << " ";                                                   \
      }                                                                        \
      cout << endl;                                                            \
    }                                                                          \
  } while (0)

typedef long long ll;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  // n == height
  // m == width
  int n, m;
  cin >> n >> m;

  if ((n % 2 != 0) && (m % 2 != 0)) {
    cout << -1 << endl;
  }

  if (n % 2 == 0) {
    for (int i = 0; i < n; i++) {
      if (i == 0) {
        for (int j = 0; j < m; j++) {
          if (j == m - 1)
            cout << "D";
          else {
            cout << (i % 2 == 0 ? "R" : "L");
          }
        }
      } else {
        for (int j = 1; j < m; j++) {
          if (j == m - 1)
            cout << (i == n - 1 ? "L" : "D");
          else {
            cout << (i % 2 == 0 ? "R" : "L");
          }
        }
      }
    }
    for (int i = 0; i < n - 1; i++) {
      cout << "U";
    }
    cout << endl;
  } else {
    for (int i = 0; i < m; i++) {
      if (i == 0) {
        for (int j = 0; j < n; j++) {
          if (j == n - 1)
            cout << "R";
          else {
            cout << (i % 2 == 0 ? "D" : "U");
          }
        }
      } else {
        for (int j = 1; j < n; j++) {
          if (j == n - 1)
            cout << (i == m - 1 ? "U" : "R");
          else {
            cout << (i % 2 == 0 ? "D" : "U");
          }
        }
      }
    }
    for (int i = 0; i < m-1; i++) {
      cout << "L";
    }
    cout << endl;
  }
  return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: ACCEPTED

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED