結果

問題 No.2337 Equidistant
ユーザー tokusakurai
提出日時 2023-06-02 21:49:08
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 264 ms / 4,000 ms
コード長 9,638 bytes
コンパイル時間 2,457 ms
コンパイル使用メモリ 207,948 KB
最終ジャッジ日時 2025-02-13 18:02:37
ジャッジサーバーID
(参考情報)
judge3 / judge2
このコードへのチャレンジ
(要ログイン)
ファイルパターン 結果
sample AC * 1
other AC * 28
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define per(i, n) for (int i = (n)-1; i >= 0; i--)
#define rep2(i, l, r) for (int i = (l); i < (r); i++)
#define per2(i, l, r) for (int i = (r)-1; i >= (l); i--)
#define each(e, v) for (auto &e : v)
#define MM << " " <<
#define pb push_back
#define eb emplace_back
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
template <typename T>
using minheap = priority_queue<T, vector<T>, greater<T>>;
template <typename T>
using maxheap = priority_queue<T>;
template <typename T>
bool chmax(T &x, const T &y) {
return (x < y) ? (x = y, true) : false;
}
template <typename T>
bool chmin(T &x, const T &y) {
return (x > y) ? (x = y, true) : false;
}
template <typename T>
int flg(T x, int i) {
return (x >> i) & 1;
}
int pct(int x) { return __builtin_popcount(x); }
int pct(ll x) { return __builtin_popcountll(x); }
int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
int botbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int botbit(ll x) { return (x == 0 ? -1 : __builtin_ctzll(x)); }
template <typename T>
void print(const vector<T> &v, T x = 0) {
int n = v.size();
for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' ');
if (v.empty()) cout << '\n';
}
template <typename T>
void printn(const vector<T> &v, T x = 0) {
int n = v.size();
for (int i = 0; i < n; i++) cout << v[i] + x << '\n';
}
template <typename T>
int lb(const vector<T> &v, T x) {
return lower_bound(begin(v), end(v), x) - begin(v);
}
template <typename T>
int ub(const vector<T> &v, T x) {
return upper_bound(begin(v), end(v), x) - begin(v);
}
template <typename T>
void rearrange(vector<T> &v) {
sort(begin(v), end(v));
v.erase(unique(begin(v), end(v)), end(v));
}
template <typename T>
vector<int> id_sort(const vector<T> &v, bool greater = false) {
int n = v.size();
vector<int> ret(n);
iota(begin(ret), end(ret), 0);
sort(begin(ret), end(ret), [&](int i, int j) { return greater ? v[i] > v[j] : v[i] < v[j]; });
return ret;
}
template <typename T>
void reorder(vector<T> &a, const vector<int> &ord) {
int n = a.size();
vector<T> b(n);
for (int i = 0; i < n; i++) b[i] = a[ord[i]];
swap(a, b);
}
template <typename T>
T floor(T x, T y) {
assert(y != 0);
if (y < 0) x = -x, y = -y;
return (x >= 0 ? x / y : (x - y + 1) / y);
}
template <typename T>
T ceil(T x, T y) {
assert(y != 0);
if (y < 0) x = -x, y = -y;
return (x >= 0 ? (x + y - 1) / y : x / y);
}
template <typename S, typename T>
pair<S, T> operator+(const pair<S, T> &p, const pair<S, T> &q) {
return make_pair(p.first + q.first, p.second + q.second);
}
template <typename S, typename T>
pair<S, T> operator-(const pair<S, T> &p, const pair<S, T> &q) {
return make_pair(p.first - q.first, p.second - q.second);
}
template <typename S, typename T>
istream &operator>>(istream &is, pair<S, T> &p) {
S a;
T b;
is >> a >> b;
p = make_pair(a, b);
return is;
}
template <typename S, typename T>
ostream &operator<<(ostream &os, const pair<S, T> &p) {
return os << p.first << ' ' << p.second;
}
struct io_setup {
io_setup() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout << fixed << setprecision(15);
}
} io_setup;
constexpr int inf = (1 << 30) - 1;
constexpr ll INF = (1LL << 60) - 1;
// constexpr int MOD = 1000000007;
constexpr int MOD = 998244353;
template <bool directed = false>
struct Heavy_Light_Decomposition {
struct edge {
int to, id;
edge(int to, int id) : to(to), id(id) {}
};
vector<vector<edge>> es;
vector<int> par, si, depth;
vector<int> root; //
vector<int> id_v, id_e; // ( 1,2,...,n-1 )
vector<int> vs;
const int n;
int m;
Heavy_Light_Decomposition(int n) : es(n), par(n), si(n, 1), depth(n, -1), root(n), id_v(n), id_e(n - 1), vs(n), n(n), m(0) {}
void add_edge(int from, int to) {
es[from].emplace_back(to, m);
if (!directed) es[to].emplace_back(from, m);
m++;
}
int bfs_sz(int r, int s) {
int t = s;
queue<int> que;
que.push(r);
depth[r] = 0;
vs[t++] = r;
while (!que.empty()) {
int i = que.front();
que.pop();
for (auto &e : es[i]) {
if (depth[e.to] != -1) continue;
par[e.to] = i;
depth[e.to] = depth[i] + 1;
vs[t++] = e.to;
que.push(e.to);
}
}
for (int i = t - 1; i >= s; i--) {
for (auto &e : es[vs[i]]) {
if (e.to != par[vs[i]]) si[vs[i]] += si[e.to];
}
}
return t;
}
void bfs_hld(int r, int s) {
id_v[r] = s;
root[r] = r;
queue<int> que;
que.push(r);
while (!que.empty()) {
int i = que.front();
que.pop();
edge heavy = {-1, -1};
int ma = 0;
for (auto &e : es[i]) {
if (e.to == par[i]) continue;
if (ma < si[e.to]) ma = si[e.to], heavy = e;
}
int cnt = id_v[i] + 1;
if (heavy.id != -1) {
root[heavy.to] = root[i];
id_e[heavy.id] = cnt;
id_v[heavy.to] = cnt;
que.push(heavy.to);
cnt += si[heavy.to];
}
for (auto &e : es[i]) {
if (e.to == par[i] || e.id == heavy.id) continue;
root[e.to] = e.to;
id_e[e.id] = cnt;
id_v[e.to] = cnt;
que.push(e.to);
cnt += si[e.to];
}
}
}
void decompose() {
int s = 0;
for (int i = 0; i < n; i++) {
if (depth[i] != -1) continue;
int t = bfs_sz(i, s);
bfs_hld(i, s);
s = t;
}
for (int i = 0; i < n; i++) vs[id_v[i]] = i;
}
int lca(int u, int v) {
while (root[u] != root[v]) {
if (depth[root[u]] > depth[root[v]]) swap(u, v);
v = par[root[v]];
}
if (depth[u] > depth[v]) swap(u, v);
return u;
}
int dist(int u, int v) { return depth[u] + depth[v] - depth[lca(u, v)] * 2; }
// u k
int ancestor(int u, int k) {
if (k > depth[u]) return -1;
while (k > 0) {
int r = root[u];
int l = depth[u] - depth[r];
if (k <= l) return vs[id_v[r] + l - k];
u = par[r];
k -= l + 1;
}
return u;
}
// u v k
int move(int u, int v, int k) {
int w = lca(u, v);
int l = depth[u] + depth[v] - depth[w] * 2;
if (k > l) return -1;
if (k <= depth[u] - depth[w]) return ancestor(u, k);
return ancestor(v, l - k);
}
//
vector<pair<int, int>> get_path(int u, int v, bool use_edge = false) {
vector<pair<int, int>> ret;
while (root[u] != root[v]) {
if (depth[root[u]] > depth[root[v]]) swap(u, v);
ret.emplace_back(id_v[root[v]], id_v[v] + 1);
v = par[root[v]];
}
if (depth[u] > depth[v]) swap(u, v);
ret.emplace_back(id_v[u] + use_edge, id_v[v] + 1);
return ret;
}
// (l > r [r,l)l < r [l,r))
vector<pair<int, int>> get_path_noncommutative(int u, int v, bool use_edge = false) {
vector<pair<int, int>> l, r;
while (root[u] != root[v]) {
if (depth[root[u]] > depth[root[v]]) {
l.emplace_back(id_v[u] + 1, id_v[root[u]]);
u = par[root[u]];
} else {
r.emplace_back(id_v[root[v]], id_v[v] + 1);
v = par[root[v]];
}
}
if (depth[u] > depth[v]) {
l.emplace_back(id_v[u] + 1, id_v[v] + use_edge);
} else {
r.emplace_back(id_v[u] + use_edge, id_v[v] + 1);
}
reverse(begin(r), end(r));
for (auto &e : r) l.push_back(e);
return l;
}
};
void solve() {
int N, Q;
cin >> N >> Q;
Heavy_Light_Decomposition G(N);
rep(i, N - 1) {
int u, v;
cin >> u >> v;
u--, v--;
G.add_edge(u, v);
}
G.decompose();
while (Q--) {
int u, v;
cin >> u >> v;
u--, v--;
int d = G.dist(u, v);
if (d % 2 == 1) {
cout << "0\n";
continue;
}
d /= 2;
if (G.depth[u] < G.depth[v]) swap(u, v);
if (G.depth[u] > G.depth[v]) {
int w1 = G.ancestor(u, d), w2 = G.ancestor(u, d - 1);
cout << G.si[w1] - G.si[w2] << '\n';
} else {
int w1 = G.ancestor(u, d), w2 = G.ancestor(u, d - 1), w3 = G.ancestor(v, d - 1);
cout << N - G.si[w2] - G.si[w3] << '\n';
}
}
}
int main() {
int T = 1;
// cin >> T;
while (T--) solve();
}
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