結果

問題 No.2337 Equidistant
ユーザー hitonanodehitonanode
提出日時 2023-06-02 21:45:07
言語 C++23
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 217 ms / 4,000 ms
コード長 14,464 bytes
コンパイル時間 2,065 ms
コンパイル使用メモリ 190,576 KB
実行使用メモリ 24,260 KB
最終ジャッジ日時 2024-12-28 17:06:44
合計ジャッジ時間 8,501 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge4
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
5,248 KB
testcase_01 AC 1 ms
5,248 KB
testcase_02 AC 1 ms
5,248 KB
testcase_03 AC 1 ms
5,248 KB
testcase_04 AC 2 ms
5,248 KB
testcase_05 AC 2 ms
5,248 KB
testcase_06 AC 3 ms
5,248 KB
testcase_07 AC 3 ms
5,248 KB
testcase_08 AC 3 ms
5,248 KB
testcase_09 AC 3 ms
5,248 KB
testcase_10 AC 3 ms
5,248 KB
testcase_11 AC 213 ms
22,016 KB
testcase_12 AC 205 ms
22,144 KB
testcase_13 AC 197 ms
22,112 KB
testcase_14 AC 202 ms
22,204 KB
testcase_15 AC 209 ms
22,072 KB
testcase_16 AC 210 ms
22,108 KB
testcase_17 AC 212 ms
22,232 KB
testcase_18 AC 210 ms
22,108 KB
testcase_19 AC 211 ms
22,144 KB
testcase_20 AC 208 ms
22,068 KB
testcase_21 AC 154 ms
22,912 KB
testcase_22 AC 162 ms
24,260 KB
testcase_23 AC 182 ms
23,544 KB
testcase_24 AC 188 ms
22,376 KB
testcase_25 AC 196 ms
23,544 KB
testcase_26 AC 194 ms
22,228 KB
testcase_27 AC 205 ms
23,552 KB
testcase_28 AC 217 ms
23,668 KB
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 # 

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <deque>
#include <forward_list>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using lint = long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template <typename T, typename V>
void ndarray(vector<T>& vec, const V& val, int len) { vec.assign(len, val); }
template <typename T, typename V, typename... Args> void ndarray(vector<T>& vec, const V& val, int len, Args... args) { vec.resize(len), for_each(begin(vec), end(vec), [&](T& v) { ndarray(v, val, args...); }); }
template <typename T> bool chmax(T &m, const T q) { return m < q ? (m = q, true) : false; }
template <typename T> bool chmin(T &m, const T q) { return m > q ? (m = q, true) : false; }
const std::vector<std::pair<int, int>> grid_dxs{{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
int floor_lg(long long x) { return x <= 0 ? -1 : 63 - __builtin_clzll(x); }
template <class T1, class T2> T1 floor_div(T1 num, T2 den) { return (num > 0 ? num / den : -((-num + den - 1) / den)); }
template <class T1, class T2> std::pair<T1, T2> operator+(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first + r.first, l.second + r.second); }
template <class T1, class T2> std::pair<T1, T2> operator-(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first - r.first, l.second - r.second); }
template <class T> std::vector<T> sort_unique(std::vector<T> vec) { sort(vec.begin(), vec.end()), vec.erase(unique(vec.begin(), vec.end()), vec.end()); return vec; }
template <class T> int arglb(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::lower_bound(v.begin(), v.end(), x)); }
template <class T> int argub(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::upper_bound(v.begin(), v.end(), x)); }
template <class IStream, class T> IStream &operator>>(IStream &is, std::vector<T> &vec) { for (auto &v : vec) is >> v; return is; }

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec);
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr);
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const pair<T, U> &pa);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa);
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp);
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp);
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl);

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec) { os << '['; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr) { os << '['; for (auto v : arr) os << v << ','; os << ']'; return os; }
template <class... T> std::istream &operator>>(std::istream &is, std::tuple<T...> &tpl) { std::apply([&is](auto &&... args) { ((is >> args), ...);}, tpl); return is; }
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl) { os << '('; std::apply([&os](auto &&... args) { ((os << args << ','), ...);}, tpl); return os << ')'; }
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa) { return os << '(' << pa.first << ',' << pa.second << ')'; }
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
#ifdef HITONANODE_LOCAL
const string COLOR_RESET = "\033[0m", BRIGHT_GREEN = "\033[1;32m", BRIGHT_RED = "\033[1;31m", BRIGHT_CYAN = "\033[1;36m", NORMAL_CROSSED = "\033[0;9;37m", RED_BACKGROUND = "\033[1;41m", NORMAL_FAINT = "\033[0;2m";
#define dbg(x) std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl
#define dbgif(cond, x) ((cond) ? std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl : std::cerr)
#else
#define dbg(x) ((void)0)
#define dbgif(cond, x) ((void)0)
#endif


#include <algorithm>
#include <cassert>
#include <functional>
#include <queue>
#include <stack>
#include <utility>
#include <vector>

// Heavy-Light Decomposition of trees
// Based on http://beet-aizu.hatenablog.com/entry/2017/12/12/235950
struct HeavyLightDecomposition {
    int V;
    int k;
    int nb_heavy_path;
    std::vector<std::vector<int>> e;
    std::vector<int> par;         // par[i] = parent of vertex i (Default: -1)
    std::vector<int> depth;       // depth[i] = distance between root and vertex i
    std::vector<int> subtree_sz;  // subtree_sz[i] = size of subtree whose root is i
    std::vector<int> heavy_child; // heavy_child[i] = child of vertex i on heavy path (Default: -1)
    std::vector<int> tree_id;     // tree_id[i] = id of tree vertex i belongs to
    std::vector<int> aligned_id,
        aligned_id_inv;    // aligned_id[i] =  aligned id for vertex i (consecutive on heavy edges)
    std::vector<int> head; // head[i] = id of vertex on heavy path of vertex i, nearest to root
    std::vector<int> head_ids;      // consist of head vertex id's
    std::vector<int> heavy_path_id; // heavy_path_id[i] = heavy_path_id for vertex [i]

    HeavyLightDecomposition(int sz = 0)
        : V(sz), k(0), nb_heavy_path(0), e(sz), par(sz), depth(sz), subtree_sz(sz), heavy_child(sz),
          tree_id(sz, -1), aligned_id(sz), aligned_id_inv(sz), head(sz), heavy_path_id(sz, -1) {}
    void add_edge(int u, int v) {
        e[u].emplace_back(v);
        e[v].emplace_back(u);
    }

    void _build_dfs(int root) {
        std::stack<std::pair<int, int>> st;
        par[root] = -1;
        depth[root] = 0;
        st.emplace(root, 0);
        while (!st.empty()) {
            int now = st.top().first;
            int &i = st.top().second;
            if (i < (int)e[now].size()) {
                int nxt = e[now][i++];
                if (nxt == par[now]) continue;
                par[nxt] = now;
                depth[nxt] = depth[now] + 1;
                st.emplace(nxt, 0);
            } else {
                st.pop();
                int max_sub_sz = 0;
                subtree_sz[now] = 1;
                heavy_child[now] = -1;
                for (auto nxt : e[now]) {
                    if (nxt == par[now]) continue;
                    subtree_sz[now] += subtree_sz[nxt];
                    if (max_sub_sz < subtree_sz[nxt])
                        max_sub_sz = subtree_sz[nxt], heavy_child[now] = nxt;
                }
            }
        }
    }

    void _build_bfs(int root, int tree_id_now) {
        std::queue<int> q({root});
        while (!q.empty()) {
            int h = q.front();
            q.pop();
            head_ids.emplace_back(h);
            for (int now = h; now != -1; now = heavy_child[now]) {
                tree_id[now] = tree_id_now;
                aligned_id[now] = k++;
                aligned_id_inv[aligned_id[now]] = now;
                heavy_path_id[now] = nb_heavy_path;
                head[now] = h;
                for (int nxt : e[now])
                    if (nxt != par[now] and nxt != heavy_child[now]) q.push(nxt);
            }
            nb_heavy_path++;
        }
    }

    void build(std::vector<int> roots = {0}) {
        int tree_id_now = 0;
        for (auto r : roots) _build_dfs(r), _build_bfs(r, tree_id_now++);
    }

    template <class T> std::vector<T> segtree_rearrange(const std::vector<T> &data) const {
        assert(int(data.size()) == V);
        std::vector<T> ret;
        ret.reserve(V);
        for (int i = 0; i < V; i++) ret.emplace_back(data[aligned_id_inv[i]]);
        return ret;
    }

    // query for vertices on path [u, v] (INCLUSIVE)
    void
    for_each_vertex(int u, int v, const std::function<void(int ancestor, int descendant)> &f) const {
        while (true) {
            if (aligned_id[u] > aligned_id[v]) std::swap(u, v);
            f(std::max(aligned_id[head[v]], aligned_id[u]), aligned_id[v]);
            if (head[u] == head[v]) break;
            v = par[head[v]];
        }
    }

    void for_each_vertex_noncommutative(
        int from, int to, const std::function<void(int ancestor, int descendant)> &fup,
        const std::function<void(int ancestor, int descendant)> &fdown) const {
        int u = from, v = to;
        const int lca = lowest_common_ancestor(u, v), dlca = depth[lca];
        while (u >= 0 and depth[u] > dlca) {
            const int p = (depth[head[u]] > dlca ? head[u] : lca);
            fup(aligned_id[p] + (p == lca), aligned_id[u]), u = par[p];
        }
        static std::vector<std::pair<int, int>> lrs;
        int sz = 0;
        while (v >= 0 and depth[v] >= dlca) {
            const int p = (depth[head[v]] >= dlca ? head[v] : lca);
            if (int(lrs.size()) == sz) lrs.emplace_back(0, 0);
            lrs.at(sz++) = {p, v}, v = par.at(p);
        }
        while (sz--) fdown(aligned_id[lrs.at(sz).first], aligned_id[lrs.at(sz).second]);
    }

    // query for edges on path [u, v]
    void for_each_edge(int u, int v, const std::function<void(int, int)> &f) const {
        while (true) {
            if (aligned_id[u] > aligned_id[v]) std::swap(u, v);
            if (head[u] != head[v]) {
                f(aligned_id[head[v]], aligned_id[v]);
                v = par[head[v]];
            } else {
                if (u != v) f(aligned_id[u] + 1, aligned_id[v]);
                break;
            }
        }
    }

    // lowest_common_ancestor: O(log V)
    int lowest_common_ancestor(int u, int v) const {
        assert(tree_id[u] == tree_id[v] and tree_id[u] >= 0);
        while (true) {
            if (aligned_id[u] > aligned_id[v]) std::swap(u, v);
            if (head[u] == head[v]) return u;
            v = par[head[v]];
        }
    }

    int distance(int u, int v) const {
        assert(tree_id[u] == tree_id[v] and tree_id[u] >= 0);
        return depth[u] + depth[v] - 2 * depth[lowest_common_ancestor(u, v)];
    }

    // Level ancestor, O(log V)
    // if k-th parent is out of range, return -1
    int kth_parent(int v, int k) const {
        if (k < 0) return -1;
        while (v >= 0) {
            int h = head.at(v), len = depth.at(v) - depth.at(h);
            if (k <= len) return aligned_id_inv.at(aligned_id.at(v) - k);
            k -= len + 1, v = par.at(h);
        }
        return -1;
    }

    // Jump on tree, O(log V)
    int s_to_t_by_k_steps(int s, int t, int k) const {
        if (k < 0) return -1;
        if (k == 0) return s;
        int lca = lowest_common_ancestor(s, t);
        if (k <= depth.at(s) - depth.at(lca)) return kth_parent(s, k);
        return kth_parent(t, depth.at(s) + depth.at(t) - depth.at(lca) * 2 - k);
    }
};

int main() {
    int N, Q;
    cin >> N >> Q;
    HeavyLightDecomposition hld(N);
    REP(e, N - 1) {
        int a, b;
        cin >> a >> b;
        --a, --b;
        hld.add_edge(a, b);
    }
    int root = 0;
    hld.build({root});

    while (Q--) {
        int s, t;
        cin >> s >> t;
        --s, --t;
        assert(s != t);
        int d = hld.distance(s, t);
        if (d % 2) {
            cout << "0\n";
            continue;
        }
        const int r = hld.s_to_t_by_k_steps(s, t, d / 2);
        int ret = N;
        REP(_, 2) {
            int u = hld.s_to_t_by_k_steps(r, s, 1);
            if (hld.par.at(u) == r) {
                ret -= hld.subtree_sz.at(u);
            } else {
                assert(hld.par.at(r) == u);
                ret -= N - hld.subtree_sz.at(r);
            }
            swap(s, t);
        }
        cout << ret << '\n';
    }
}
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