結果
| 問題 |
No.2337 Equidistant
|
| コンテスト | |
| ユーザー |
 dyktr_06
|
| 提出日時 | 2023-06-02 23:29:47 |
| 言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
| 結果 |
AC
|
| 実行時間 | 1,807 ms / 4,000 ms |
| コード長 | 8,830 bytes |
| コンパイル時間 | 5,755 ms |
| コンパイル使用メモリ | 272,684 KB |
| 最終ジャッジ日時 | 2025-02-13 20:59:40 |
|
ジャッジサーバーID （参考情報） |
judge3 / judge3 |
（要ログイン）
| ファイルパターン | 結果 |
|---|---|
| sample | AC * 1 |
| other | AC * 28 |
ソースコード
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define overload4(_1, _2, _3, _4, name, ...) name
#define rep1(n) for(int i = 0; i < (int)(n); ++i)
#define rep2(i, n) for(int i = 0; i < (int)(n); ++i)
#define rep3(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep4(i, a, b, c) for(int i = (a); i < (int)(b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; --i)
#define ALL(a) a.begin(), a.end()
#define Sort(a) sort(a.begin(), a.end())
#define RSort(a) sort(a.rbegin(), a.rend())
typedef long long int ll;
typedef unsigned long long ul;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<char> vc;
typedef vector<string> vst;
typedef vector<double> vd;
typedef vector<long double> vld;
typedef pair<long long, long long> P;
template<class T> long long sum(const T& a){ return accumulate(a.begin(), a.end(), 0LL); }
template<class T> auto min(const T& a){ return *min_element(a.begin(), a.end()); }
template<class T> auto max(const T& a){ return *max_element(a.begin(), a.end()); }
const long long MINF = 0x7fffffffffff;
const long long INF = 0x1fffffffffffffff;
const long long MOD = 1000000007;
const long double EPS = 1e-9;
const long double PI = acos(-1);
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p){ is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){ os << "(" << p.first << ", " << p.second << ")"; return os; }
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for(T &in : v) is >> in; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v){ for(int i = 0; i < (int) v.size(); ++i){ os << v[i] << (i + 1 != (int) v.size() ? " " : ""); } return os; }
template <typename T, typename S> ostream &operator<<(ostream &os, const map<T, S> &mp){ for(auto &[key, val] : mp){ os << key << ":" << val << " "; } return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, queue<T> q){ while(q.size()){ os << q.front() << " "; q.pop(); } return os; }
template <typename T> ostream &operator<<(ostream &os, deque<T> q){ while(q.size()){ os << q.front() << " "; q.pop_front(); } return os; }
template <typename T> ostream &operator<<(ostream &os, stack<T> st){ while(st.size()){ os << st.top() << " "; st.pop(); } return os; }
template <class T, class Container, class Compare> ostream &operator<<(ostream &os, priority_queue<T, Container, Compare> pq){ while(pq.size()){ os << pq.top() << " "; pq.pop(); } return os; }
template<class T, class U> inline T vin(T& vec, U n) { vec.resize(n); for(int i = 0; i < (int) n; ++i) cin >> vec[i]; return vec; }
template<class T> inline void vout(T vec, string s = "\n"){ for(auto x : vec) cout << x << s; }
template<class... T> void in(T&... a){ (cin >> ... >> a); }
void out(){ cout << '\n'; }
template<class T, class... Ts> void out(const T& a, const Ts&... b){ cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class T, class U> void inGraph(vector<vector<T>>& G, U n, U m, bool directed = false){ G.resize(n); for(int i = 0; i < m; ++i){ int a, b; cin >> a >> b; a--, b--; G[a].push_back(b); if(!directed) G[b].push_back(a); } }
class HeavyLightDecomposition{
int V;
vector<vector<int>> G;
vector<int> stsize, parent, pathtop, depth, in, reverse_in, out;
int root;
private:
// Subtree Size
void buildStsize(int curr, int prev){
stsize[curr] = 1, parent[curr] = prev;
for(int &v : G[curr]){
if(v == prev){
if(v == G[curr].back()) break;
else swap(v, G[curr].back());
}
buildStsize(v, curr);
stsize[curr] += stsize[v];
if(stsize[v] > stsize[G[curr][0]]){
swap(v, G[curr][0]);
}
}
}
void buildPath(int curr, int prev, int &t){
in[curr] = t++;
reverse_in[in[curr]] = curr;
for(int v : G[curr]){
if(v == prev) continue;
if(v == G[curr][0]){
pathtop[v] = pathtop[curr];
}else{
pathtop[v] = v;
}
depth[v] = depth[curr] + 1;
buildPath(v, curr, t);
}
out[curr] = t;
}
public:
HeavyLightDecomposition(int node_size) : V(node_size), G(V), stsize(V, 0), parent(V, -1),
pathtop(V, -1), depth(V, 0), in(V, -1), reverse_in(V, -1), out(V, -1){}
void add_edge(int u, int v){
G[u].push_back(v);
G[v].push_back(u);
}
void build(int _root = 0){
root = _root;
int t = 0;
buildStsize(root, -1);
pathtop[root] = root;
buildPath(root, -1, t);
}
inline int get(int a){
return in[a];
}
int la(int a, int k) {
while(true){
int u = pathtop[a];
if(in[a] - k >= in[u]) return reverse_in[in[a] - k];
k -= in[a] - in[u] + 1;
a = parent[u];
}
}
int lca(int a, int b){
int pa = pathtop[a], pb = pathtop[b];
while(pathtop[a] != pathtop[b]){
if(in[pa] > in[pb]){
a = parent[pa], pa = pathtop[a];
}else{
b = parent[pb], pb = pathtop[b];
}
}
if(in[a] > in[b]) swap(a, b);
return a;
}
int dist(int a, int b){ return depth[a] + depth[b] - 2 * depth[lca(a, b)]; }
int jump(int from, int to, int k) {
if(!k) return from;
int l = lca(from, to);
int d = dist(from, to);
if(d < k) return -1;
if(depth[from] - depth[l] >= k) return la(from, k);
k -= depth[from] - depth[l];
return la(to, depth[to] - depth[l] - k);
}
void subtree_query(int a, const function<void(int, int)> &func){
func(in[a], out[a]);
}
void path_query(int a, int b, const function<void(int, int)> &func, bool include_root = true, bool reverse_path = false){
vector<pair<int, int>> path;
int pa = pathtop[a], pb = pathtop[b];
while(pathtop[a] != pathtop[b]){
if(in[pa] > in[pb]){
path.emplace_back(in[pa], in[a] + 1);
a = parent[pa], pa = pathtop[a];
}else{
path.emplace_back(in[pb], in[b] + 1);
b = parent[pb], pb = pathtop[b];
}
}
if(in[a] > in[b]) swap(a, b);
if(include_root) path.emplace_back(in[a], in[b] + 1);
else path.emplace_back(in[a] + 1, in[b] + 1);
if(!reverse_path) reverse(path.begin(), path.end());
else for(auto& p : path) p = make_pair(V - p.second, V - p.first);
for(auto [u, v] : path){
func(u, v);
}
}
void path_noncommutative_query(int a, int b, const function<void(int, int)> &func, const function<void(int, int)> &func2){
int l = lca(a, b);
path_query(a, l, func2, false, true);
path_query(l, b, func, true, false);
}
};
map<ll, map<ll, ll>> e;
ll n, q;
vector<vll> G;
ll dfs(ll curr, ll prev){
ll res = 1;
for(auto x : G[curr]){
if(x == prev) continue;
res += dfs(x, curr);
}
if(prev != -1){
e[prev][curr] = res;
e[curr][prev] = n - res;
}
return res;
}
void input(){
in(n, q);
}
void solve(){
HeavyLightDecomposition hl(n);
G.resize(n);
rep(i, n - 1){
ll a, b; in(a, b); a--, b--;
hl.add_edge(a, b);
G[a].push_back(b);
G[b].push_back(a);
}
hl.build();
dfs(0, -1);
while(q--){
ll s, t; in(s, t);
s--, t--;
ll d = hl.dist(s, t);
if(d % 2){
out(0);
}else{
ll u = hl.jump(s, t, d / 2);
ll ans = n;
ans -= e[u][hl.jump(u, s, 1)];
ans -= e[u][hl.jump(u, t, 1)];
out(ans);
}
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout << fixed << setprecision(20);
input();
solve();
}