Submission #74717991

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Source Code Expand

#include<bits/extc++.h>
 
#pragma GCC optimize("O3","unroll-loops")
#pragma GCC target("avx,avx2")
 
#include<iostream>
#include<queue>
#include<vector>
#include<cmath>
#include<map>
 
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
 
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
 
#define coutc "\033[48;5;196m\033[38;5;15m"
#define endc "\033[0m"
#define M(_1, _2, _3, _4, NAME, ...) NAME
#define rep(...) \
  M(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rep4(_, x, n, s) \
  for (int _ = x; (s < 0) ? _ > n : _ < n; _ += s)
#define rep3(_, x, n) rep4(_, x, n, (x < n ? 1 : -1))
#define rep2(_, n) rep3(_, 0, n)
#define rep1(n) rep2(i, n)
 
#define FOR(i, a, b) for (int i=a; i<b; i++)
#define F0R(i, a) for (int i=0; i<a; i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) a*b/gcd(a,b)
 
#define mp make_pair
// #define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define endl "\n"
 
// #define cin fin
// #define cout fout
 
// ifstream fin("word.in");
// ofstream fout("word.out");
 
const int inf = INT_MAX;
const int MOD = 1000000007;
double PI = 4*atan(1);
 
#ifdef DEBUG
string to_string(char c) { return string({c}); }
// 7
template<class... Ts>
ostream& operator<<(ostream& o, tuple<Ts...> t) {
  string s = "(";
  apply([&](auto&&... r) {
    ((s += to_string(r) + ", "), ...); }, t);
  return o << s.substr(0, len(s) - 2) + ")";
}
// 3
ostream& operator<<(ostream &o, pair<auto, auto> p) {
  return o << "(" << p.fi << ", " << p.se << ")";
}
// 7
template<class C, class T = typename C::value_type,
typename std::enable_if<!std::is_same<C, std::string>
::value>::type* = nullptr>
ostream& operator<<(ostream &o, C c) {
  for (auto e : c) o << setw(7) << right << e;
  return o << endc << endl << coutc;
}
// 7
void debug(const auto &e, const auto &... r) {
  cout << coutc << e;
  ((cout << " " << r), ..., (cout << endc << endl));
}
#else
#define debug(...)
#endif
 
map<string,int> mon;
map<int,string> inp;

ll pw(ll a, ll e) {
    ll r = 1;
    while (e) {
        if (e & 1) r = r * a % 998244353;
        a = a * a % 998244353;
        e >>= 1;
    }
    return r;
}
 
void _main(int tc) {
    if (tc == 0) {
        int T;
        cin >> T;
        rep(i, T) _main(i + 1);
        return;
    }
    int N, K;
    cin >> N >> K;
    vector<vi> g(N + 1);
    int i = 0;
    while (i < N - 1) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
        i++;
    }
    vi p(N + 1), ord;
    ord.reserve(N);
    stack<int> st;
    st.push(1);
    p[1] = -1;
    while (!st.empty()) {
        int u = st.top();
        st.pop();
        ord.push_back(u);
        int j = 0;
        while (j < (int)g[u].size()) {
            int v = g[u][j];
            if (v != p[u]) {
                p[v] = u;
                st.push(v);
            }
            j++;
        }
    }
    vi sz(N + 1, 1);
    ll s0 = 0;
    i = N - 1;
    while (i > 0) {
        int u = ord[i];
        s0 = (s0 + 1LL * sz[u] * (N - sz[u])) % 998244353;
        sz[p[u]] += sz[u];
        i--;
    }
    ll up = 1LL * (N + K - 1) % 998244353 * (N + K) % 998244353 * (N + K + 1) % 998244353;
    ll dn = 1LL * (N - 1) % 998244353 * N % 998244353 * (N + 1) % 998244353;
    ll ans = s0 * up % 998244353 * pw(dn, 998244353 - 2) % 998244353;
    cout << ans << endl;
}
// 5
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  _main(0), exit(0);
  int tc; cin >> tc; rep(i, tc) _main(i + 1);
}

Submission Info

Judge Result