Astralis session I

input/code.cpp: In function 'int dfs(std::vector<bool>, std::vector<std::vector<int> >&, int, int, int)':
input/code.cpp:28:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<bool>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |         for (int i = 1; i < nodes.size(); ++i){
      |                         ~~^~~~~~~~~~~~~~

using namespace std;

#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
#include <unordered_set>  


void colour(vector<bool>& nodes, vector< vector<int> >&e, int k, int parent, bool col){
    nodes[k] = col;
    for (auto i = begin(e[k]); i != end(e[k]); ++i) {
        if (*i != parent)
            colour(nodes, e, (*i), k, col);
    }
}

int dfs(vector<bool> nodes, vector< vector<int> >&e, int k, int parent, int n){
    int sum = 1;
    for (auto i = begin(e[k]); i != end(e[k]); ++i) {
        if (*i != parent)
            sum += dfs(nodes, e, (*i), k, n);
    }
    if (sum == n /2 ){
        colour(nodes, e, k, parent, false);
        colour(nodes, e, parent, k, true);
        cout << "Yes" << endl;
        for (int i = 1; i < nodes.size(); ++i){
            if (nodes[i])
                cout << "M";
            else
                cout << "U";
        }
        cout <<endl;
        exit(0);
    }
    return sum;
}




int main(){

    int n;

    cin >> n;

    vector< vector<int> > adj = vector<vector<int> >(n+1);
    for (int i = 0; i < n-1; ++i)
    {
        int aux1, aux2;

        cin >> aux1 >> aux2;

        adj[aux1].push_back(aux2);
        adj[aux2].push_back(aux1);
        
    }

    vector<bool> nodes = vector<bool>(n+1);

    dfs(nodes, adj, 1, -1, n);

    cout << "No" << endl;

}   

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

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: ACCEPTED