#877332 (C++17) No.2337 Equidistant

• 問題: No.2337 Equidistant
• ユーザー: jabee
• 提出日時: 2023-06-02 22:43:56
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: WA
• 実行時間: -
• コード長: 8,455 bytes
• コンパイル時間: 4,760 ms
• コンパイル使用メモリ: 271,784 KB
• 最終ジャッジ日時: 2025-02-13 19:42:43
• ジャッジサーバーID （参考情報）: judge3 / judge1

ファイルパターン	結果
sample	AC * 1
other	AC * 5 WA * 23

ソースコード

#include<bits/stdc++.h>
#include <math.h>
#include <algorithm>
#include <iostream>
#include <vector>
#include <atcoder/all>
#include <atcoder/dsu>
#include <atcoder/segtree>
#include <atcoder/lazysegtree>
#include <atcoder/modint>
#include <atcoder/scc>
#include <chrono>
#include <random>
#include <cassert>
#ifndef templete
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()

//#include<boost/multiprecision/cpp_int.hpp>
//using namespace boost::multiprecision;
using namespace std;
using namespace atcoder;
//using atmint = modint998244353;
using atmint = modint;
using Graph = vector<vector<int>>;
using P = pair<long long,long long>;
//#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60;
template<class T>bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }

//---------------------------------------------------------------------------------------------------

template<int MOD> struct ModInt {
    static const int Mod = MOD; unsigned x; ModInt() : x(0) { }
    ModInt(signed sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    ModInt(signed long long sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    int get() const { return (int)x; }
    ModInt &operator+=(ModInt that) { if ((x += that.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator-=(ModInt that) { if ((x += MOD - that.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % MOD; return *this; }
    ModInt &operator/=(ModInt that) { return *this *= that.inverse(); }
    ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
    ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
    ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
    ModInt operator/(ModInt that) const { return ModInt(*this) /= that; }
    ModInt inverse() const { long long a = x, b = MOD, u = 1, v = 0;
        while (b) { long long t = a / b; a -= t * b; std::swap(a, b); u -= t * v; std::swap(u, v); }
        return ModInt(u); }
    bool operator==(ModInt that) const { return x == that.x; }
    bool operator!=(ModInt that) const { return x != that.x; }
    ModInt operator-() const { ModInt t; t.x = x == 0 ? 0 : Mod - x; return t; }
};
template<int MOD> ostream& operator<<(ostream& st, const ModInt<MOD> a) { st << a.get(); return st; };
template<int MOD> ModInt<MOD> operator^(ModInt<MOD> a, unsigned long long k) {
    ModInt<MOD> r = 1; while (k) { if (k & 1) r *= a; a *= a; k >>= 1; } return r; }
template<typename T, int FAC_MAX> struct Comb { vector<T> fac, ifac;
    Comb(){fac.resize(FAC_MAX,1);ifac.resize(FAC_MAX,1);rep(i,1,FAC_MAX)fac[i]=fac[i-1]*i;
        ifac[FAC_MAX-1]=T(1)/fac[FAC_MAX-1];rrep(i,FAC_MAX-2,1)ifac[i]=ifac[i+1]*T(i+1);}
    T aPb(int a, int b) { if (b < 0 || a < b) return T(0); return fac[a] * ifac[a - b]; }
    T aCb(int a, int b) { if (b < 0 || a < b) return T(0); return fac[a] * ifac[a - b] * ifac[b]; }
    T nHk(int n, int k) { if (n == 0 && k == 0) return T(1); if (n <= 0 || k < 0) return 0;
        return aCb(n + k - 1, k); } // nHk = (n+k-1)Ck : n is separator
    T pairCombination(int n) {if(n%2==1)return T(0);return fac[n]*ifac[n/2]/(T(2)^(n/2));}
    // combination of paris for n com.aCb(h+w-2,h-1);
}; 
//typedef ModInt<1000000007> mint;
typedef ModInt<998244353> mint; 
//typedef ModInt<1000000000> mint; 
Comb<mint, 2010101> com;
//vector dp(n+1,vector(n+1,vector<ll>(n+1,0)));
//vector dp(n+1,vector<ll>(n+1,0));
  std::random_device seed_gen;
  std::mt19937 engine(seed_gen());
string ye = "Yes"; string no = "No"; string draw = "Draw";

#endif // templete
//---------------------------------------------------------------------------------------------------
struct LCA {
    vector<vector<int>> parent;  // parent[k][u]:= u の 2^k 先の親
    vector<vector<ll>> max_w;  // max_w[k][u]:= u の 2^k 先までの辺をたどった時の最大の重み
    vector<int> dist;            // root からの距離
    vector<int> child_cnt;            // child
    LCA(const Graph &G, map<P,ll> & cost,int root = 0) { init(G, cost, root); }
    // 初期化
    void init(const Graph &G, map<P,ll> & cost, int root = 0) {
        int V = G.size();
        int K = 1;
        while ((1 << K) < V) K++;
        parent.assign(K, vector<int>(V, -1));
        max_w.assign(K, vector<ll>(V, -infl));
        dist.assign(V, -1);
        child_cnt.assign(V, 0);
        dfs(G, cost, root, -1, 0);
        for (int k = 0; k + 1 < K; k++) {
            for (int v = 0; v < V; v++) {
                if (parent[k][v] < 0) {
                    parent[k + 1][v] = -1;
                } else {
                    parent[k + 1][v] = parent[k][parent[k][v]];
                    max_w[k + 1][v] = max(max_w[k][v],max_w[k][parent[k][v]]);
                }
            }
        }
    }
    // 根からの距離と1つ先の頂点を求める
    int dfs(const Graph &G, map<P,ll> & cost, int v, int p, int d) {
        int cnt = 0;
        parent[0][v] = p;
        if(p == -1) max_w[0][v] = -infl;
        else max_w[0][v] = cost[{v,p}];
        dist[v] = d;
        for (auto e : G[v]) {
            if (e != p) cnt += dfs(G, cost, e, v, d + 1);
        }
        child_cnt[v] = cnt + 1;
        return child_cnt[v];
    }
    int query(int u, int v) {
        if (dist[u] < dist[v]) swap(u, v);  // u の方が深いとする
        int K = parent.size();
        // LCA までの距離を同じにする
        for (int k = 0; k < K; k++) {
            if ((dist[u] - dist[v]) >> k & 1) {
                u = parent[k][u];
            }
        }
        // 二分探索で LCA を求める
        if (u == v) return u;
        for (int k = K - 1; k >= 0; k--) {
            if (parent[k][u] != parent[k][v]) {
                u = parent[k][u];
                v = parent[k][v];
            }
        }
        return parent[0][u];
    }
    int query2(int u, int dep) {
        int K = parent.size();
        for (int k = 0; k < K; k++) {
            if (dep >> k & 1) {
                u = parent[k][u];
            }
        }
        return u;
    }



    // u,vとlca(u,v)間を結ぶ辺のうち、最大の重みの辺を求める
     ll query_max_w(int u, int v) {
        ll res = 0;
        if (dist[u] < dist[v]) swap(u, v);  // u の方が深いとする
        int K = parent.size();
        // LCA までの距離を同じにする
        for (int k = 0; k < K; k++) {
            if ((dist[u] - dist[v]) >> k & 1) {
                chmax(res,max_w[k][u]);
                u = parent[k][u];
            }
        }
        // 二分探索で LCA を求める
        if (u == v) return res;
        for (int k = K - 1; k >= 0; k--) {
            if (parent[k][u] != parent[k][v]) {
                chmax(res,max_w[k][u]);
                chmax(res,max_w[k][v]);
                u = parent[k][u];
                v = parent[k][v];
            }
        }
        chmax(res,max_w[0][u]);
        chmax(res,max_w[0][v]);
        return res;
    } 
  int get_dist(int u, int v) { return dist[u] + dist[v] - 2 * dist[query(u, v)]; }
  int query3(int s, int t){
      //cout << dist[s] << " " << dist[t] << endl;
      ll dis = get_dist(s,t);
      if(dis % 2 == 1){
        return 0;
      }else{
        if(dist[s] < dist[t])swap(s,t);
        ll l = query(s,t);
        if(l == s  || l == t){
        ll dep_s = query2(s,dis/2);
        ll dep_c = query2(s,dis/2 - 1);
        return child_cnt[dep_s] - child_cnt[dep_c];
        }else{
        ll dep_s = query2(s,dist[s] - dist[l] - 1);
        ll dep_c = query2(t,dist[t] - dist[l] - 1);
        return child_cnt[0] - child_cnt[dep_s] - child_cnt[dep_c];          
        }
      }
  }
  bool is_on_path(int u, int v, int a) { return get_dist(u, a) + get_dist(a, v) == get_dist(u, v); }
};

void _main() {
  ll n,q;
  cin >> n >> q;
  Graph g(n);
  rep(i,0,n-1){
    ll a,b;
    cin >> a >> b;
    a--; b--;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  map<P,ll>mp;
  LCA lca(g,mp,0);
  rep(qi,0,q){
    ll s,t;
    cin >> s >> t;
    s--; t--;
    cout << lca.query3(s,t) << endl;
  }
}