Chess board tour

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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int n, m;
    cin >> n >> m;
    
    if(n % 2 == 1 && m % 2 ==1){
        cout << "-1";
        return 0;
    }
    
    string path;
    
    if(m %2 ==0){
        for(int c=1; c<=m; c+=2){
            for(int r=1; r<n; r++){
                path += 'D';
            }
            if(c != m){
                path += 'R';
            }
            for(int r=1; r<n; r++){
                path += 'U';
            }
            if(c != m){
                path += 'L';
            }
        }
    }
    else{
        for(int r=1; r<=n; r+=2){
            for(int c=1; c<m; c++){
                path += 'R';
            }
            if(r != n){
                path += 'D';
            }
            for(int c=1; c<m; c++){
                path += 'L';
            }
            if(r != n){
                path += 'U';
            }
        }
    }
    
    if(path.length() != (size_t)(n * m)){
        cout << "-1";
        return 0;
    }
    
    cout << path;
    
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: ACCEPTED

Test 7

Verdict: WRONG ANSWER

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: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: WRONG ANSWER

Test 22

Verdict: ACCEPTED

Test 23

Verdict: WRONG ANSWER

Test 24

Verdict: WRONG ANSWER

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: WRONG ANSWER

Test 28

Verdict: WRONG ANSWER

Test 29

Verdict: WRONG ANSWER

Test 30

Verdict: WRONG ANSWER

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: WRONG ANSWER

Test 34

Verdict: WRONG ANSWER

Test 35

Verdict: WRONG ANSWER

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: ACCEPTED

Test 38

Verdict: WRONG ANSWER

Test 39

Verdict: WRONG ANSWER

Test 40

Verdict: WRONG ANSWER

Test 41

Verdict: WRONG ANSWER

Test 42

Verdict: WRONG ANSWER

Test 43

Verdict: WRONG ANSWER

Test 44

Verdict: ACCEPTED

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: WRONG ANSWER

Test 47

Verdict: WRONG ANSWER

Test 48

Verdict: WRONG ANSWER

Test 49

Verdict: WRONG ANSWER

Test 50

Verdict: WRONG ANSWER

Test 51

Verdict: WRONG ANSWER

Test 52

Verdict: ACCEPTED

Test 53

Verdict: WRONG ANSWER

Test 54

Verdict: WRONG ANSWER

Test 55

Verdict: WRONG ANSWER

Test 56

Verdict: WRONG ANSWER