Astralis session I

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define die(x) return cout << x << endl, 0
#define all(o) o.begin(), o.end()
#define endl '\n'
#define IOS ios::sync_with_stdio(0), cin.tie(0)
#define FILE freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define SZ(x) ((int)(x).size())
typedef long double ld;
typedef long long ll;
int gcd(int x,int y){ return (!y ? x : gcd(y, x%y)); }
int to_int(string sconvert){stringstream geek(sconvert);int xconvert = 0; geek >> xconvert; return xconvert;}
const int MAXN=200000+30,MAX_LOG=40,INF=1e18+10,MOD=1e9+7;
const double PI = acos(-1);
int mod(int x) { return (x % MOD + MOD) % MOD; }
int power(int x,int y){
    if(y==0)return 1;
    int c=power(x,y/2);
    c=(c*c)%MOD;
    if(y%2)c=(c*x)%MOD;
    return c;
}
 
 
int n, m;
int visited[MAXN], visited2[MAXN];
vector<int> g[MAXN];

int total_sum;
int sums[MAXN];
int final_u, final_v;
int dfs(int u){
    visited[u] = 1;
    for(int v: g[u]){
        if(!visited[v]){
            int sons = dfs(v);
            if (sons == n-sons){
                final_u = u;
                final_v = v;
            }
            sums[u] += sons;

        }
    }
    return sums[u] + 1;

}
 
void dfs2(int u, int c){
    visited2[u] = c;
    for(int v: g[u]){
        if(!visited2[v]){
            dfs2(v, c);
        }
    }

}
 

int MAIN(){
    cin>>n;
    m = n-1;
    final_u = -1;
    for (int i = 0; i < m; i++){
        int u,v;
        cin>>u>>v;
        g[u].push_back(v);
        g[v].push_back(u);

    }
    dfs(1);
    if(final_u == -1){
        cout <<"No";
        return 0;
    }
    cout<<"Yes"<<endl;

    visited2[final_u] = 1;
    visited2[final_v] = 2;
    dfs2(final_u, 1);
    dfs2(final_v, 2);
    for (int i = 1; i <= n; i++){
        if (visited2[i] == 1)cout<<"U";
        else cout<<"M";
    }
    
    
    return 0;
}
int32_t main(){
    IOS;
    int t=1;
    // cin>>t;
    while(t--)MAIN();
    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

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: ACCEPTED