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input/code.cpp: In function 'bool isSafe(int, std::vector<std::vector<bool> >&, int*, bool*, int)':
input/code.cpp:6:9: warning: unused variable 'V' [-Wunused-variable]
    6 |     int V = graph.size();
      |         ^

#include <iostream>
#include <vector>
using namespace std;

bool isSafe(int v, vector<vector<bool>>& graph, int path[], bool visited[], int pos) {
    int V = graph.size();
    if (!graph[path[pos - 1]][v]) return false;
    if (visited[v]) return false;
    return true;
}

bool hamCycleUtil(vector<vector<bool>>& graph, int path[], bool visited[], int pos) {
    int V = graph.size();
    if (pos == V) {
        return graph[path[pos - 1]][path[0]];
    }
    for (int v = 1; v < V; v++) {
        if (isSafe(v, graph, path, visited, pos)) {
            path[pos] = v;
            visited[v] = true;
            if (hamCycleUtil(graph, path, visited, pos + 1)) return true;
            path[pos] = -1;
            visited[v] = false;
        }
    }
    return false;
}

void printSolution(int path[], int V, int n, int m) {
    int from_x = 0, from_y = 0;
    for (int i = 1; i < V; i++) {
        int y = path[i] / m;
        int x = path[i] % m;
        if (y > from_y) cout << "D";
        else if (y < from_y) cout << "U";
        else if (x > from_x) cout << "R";
        else if (x < from_x) cout << "L";
        from_x = x;
        from_y = y;
    }
    if(from_y<0)cout<<"D";
    else if(from_y>0)cout<<"U";
    else if(from_x<0)cout<<"R";
    else if(from_x>0)cout<<"L";
    cout << endl;
}

bool hamCycle(vector<vector<bool>>& graph, int n, int m) {
    int V = graph.size();
    int path[V];
    bool visited[V] = {false};
    for (int i = 0; i < V; i++) path[i] = -1;
    path[0] = 0;
    visited[0] = true;
    if (!hamCycleUtil(graph, path, visited, 1)) {
        cout << -1 << endl;
        return false;
    }
    printSolution(path, V, n, m);
    return true;
}

int main() {
    int n, m;
    cin >> n >> m;
    vector<vector<bool>> adj(n * m, vector<bool>(n * m, false));

    for (int i = 0; i < n; i++) {
        for (int l = 0; l < m; l++) {
            int pos = i * m + l;
            if (i - 1 >= 0) adj[pos][(i - 1) * m + l] = true;
            if (i + 1 < n) adj[pos][(i + 1) * m + l] = true;
            if (l - 1 >= 0) adj[pos][i * m + (l - 1)] = true;
            if (l + 1 < m) adj[pos][i * m + (l + 1)] = true;
        }
    }

    hamCycle(adj, n, m);
}

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: TIME LIMIT EXCEEDED

Test 22

Verdict: ACCEPTED

Test 23

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Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

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Test 28

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Test 29

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Test 30

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Test 47

Verdict: RUNTIME ERROR

Test 48

Verdict: RUNTIME ERROR

Test 49

Verdict: RUNTIME ERROR

Test 50

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Test 51

Verdict: RUNTIME ERROR

Test 52

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Test 53

Verdict: RUNTIME ERROR

Test 54

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Test 56

Verdict: TIME LIMIT EXCEEDED