結果

問題 No.2337 Equidistant
ユーザー ebi_flyebi_fly
提出日時 2023-06-02 23:22:59
言語 C++17
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 813 ms / 4,000 ms
コード長 10,626 bytes
コンパイル時間 2,112 ms
コンパイル使用メモリ 167,344 KB
実行使用メモリ 139,988 KB
最終ジャッジ日時 2023-08-28 05:55:55
合計ジャッジ時間 13,546 ms
ジャッジサーバーID
（参考情報） 		judge14 / judge15
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
4,380 KB
testcase_01 AC 2 ms
4,376 KB
testcase_02 AC 1 ms
4,380 KB
testcase_03 AC 1 ms
4,376 KB
testcase_04 AC 1 ms
4,380 KB
testcase_05 AC 2 ms
4,380 KB
testcase_06 AC 4 ms
4,376 KB
testcase_07 AC 4 ms
4,380 KB
testcase_08 AC 4 ms
4,380 KB
testcase_09 AC 4 ms
4,380 KB
testcase_10 AC 4 ms
4,380 KB
testcase_11 AC 451 ms
111,432 KB
testcase_12 AC 461 ms
111,432 KB
testcase_13 AC 457 ms
111,412 KB
testcase_14 AC 459 ms
111,432 KB
testcase_15 AC 465 ms
111,404 KB
testcase_16 AC 459 ms
111,352 KB
testcase_17 AC 446 ms
111,436 KB
testcase_18 AC 457 ms
111,776 KB
testcase_19 AC 438 ms
111,404 KB
testcase_20 AC 449 ms
111,420 KB
testcase_21 AC 408 ms
139,988 KB
testcase_22 AC 813 ms
111,660 KB
testcase_23 AC 419 ms
112,168 KB
testcase_24 AC 600 ms
130,248 KB
testcase_25 AC 429 ms
112,024 KB
testcase_26 AC 662 ms
130,556 KB
testcase_27 AC 476 ms
112,700 KB
testcase_28 AC 488 ms
112,192 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 # 

#line 1 "a.cpp"
#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <memory>
#include <numeric>
#include <optional>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

/* macro */

#define rep(i, a, n) for (int i = (int)(a); i < (int)(n); i++)
#define rrep(i, a, n) for (int i = ((int)(n)-1); i >= (int)(a); i--)
#define Rep(i, a, n) for (i64 i = (i64)(a); i < (i64)(n); i++)
#define RRep(i, a, n) for (i64 i = ((i64)(n)-i64(1)); i >= (i64)(a); i--)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()

/* macro end */

/* template */

namespace ebi {

#ifdef LOCAL
#define debug(...)                                                      \
    std::cerr << "LINE: " << __LINE__ << "  [" << #__VA_ARGS__ << "]:", \
        debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif

void debug_out() {
    std::cerr << std::endl;
}

template <typename Head, typename... Tail> void debug_out(Head h, Tail... t) {
    std::cerr << " " << h;
    if (sizeof...(t) > 0) std::cout << " :";
    debug_out(t...);
}

template <typename T1, typename T2>
std::ostream &operator<<(std::ostream &os, const std::pair<T1, T2> &pa) {
    return os << pa.first << " " << pa.second;
}

template <typename T1, typename T2>
std::istream &operator>>(std::istream &os, std::pair<T1, T2> &pa) {
    return os >> pa.first >> pa.second;
}

template <typename T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &vec) {
    for (std::size_t i = 0; i < vec.size(); i++)
        os << vec[i] << (i + 1 == vec.size() ? "" : " ");
    return os;
}

template <typename T>
std::istream &operator>>(std::istream &os, std::vector<T> &vec) {
    for (T &e : vec) std::cin >> e;
    return os;
}

template <typename T>
std::ostream &operator<<(std::ostream &os, const std::optional<T> &opt) {
    if (opt) {
        os << opt.value();
    } else {
        os << "invalid value";
    }
    return os;
}

using std::size_t;
using i32 = std::int32_t;
using u32 = std::uint32_t;
using i64 = std::int64_t;
using u64 = std::uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;

template <class T, T init> auto make_vector(int n) {
    return std::vector<T>(n, init);
}

template <class T, T init, typename Head, typename... Tail>
auto make_vector(Head n, Tail... ts) {
    return std::vector(n, make_vector<T, init>(ts...));
}

template <class T> inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T> inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <class T> T pow(T x, i64 n) {
    T res = 1;
    while (n > 0) {
        if (n & 1) res = res * x;
        x = x * x;
        n >>= 1;
    }
    return res;
}

template <class T> T mod_pow(T x, i64 n, i64 mod) {
    T res = 1;
    while (n > 0) {
        if (n & 1) res = (res * x) % mod;
        x = (x * x) % mod;
        n >>= 1;
    }
    return res;
}

template <class T> T scan() {
    T val;
    std::cin >> val;
    return val;
}

template <class T> struct Edge {
    int to;
    T cost;
    Edge(int _to, T _cost = 1) : to(_to), cost(_cost) {}
};

template <class T> struct Graph : std::vector<std::vector<Edge<T>>> {
    using std::vector<std::vector<Edge<T>>>::vector;
    void add_edge(int u, int v, T w, bool directed = false) {
        (*this)[u].emplace_back(v, w);
        if (directed) return;
        (*this)[v].emplace_back(u, w);
    }
};

struct graph : std::vector<std::vector<int>> {
    using std::vector<std::vector<int>>::vector;
    void add_edge(int u, int v, bool directed = false) {
        (*this)[u].emplace_back(v);
        if (directed) return;
        (*this)[v].emplace_back(u);
    }
};

constexpr i64 LNF = std::numeric_limits<i64>::max() / 4;

constexpr int INF = std::numeric_limits<int>::max() / 2;

const std::vector<int> dy = {1, 0, -1, 0, 1, 1, -1, -1};
const std::vector<int> dx = {0, 1, 0, -1, 1, -1, 1, -1};

}  // namespace ebi

#line 2 "tree/lowest_common_ancestor.hpp"

#line 4 "tree/lowest_common_ancestor.hpp"

#line 2 "data_structure/sparse_table.hpp"

#line 4 "data_structure/sparse_table.hpp"

/*
    reference: https://scrapbox.io/data-structures/Sparse_Table
*/

namespace ebi {

template <class Band, Band (*op)(Band, Band)> struct sparse_table {
  public:
    sparse_table() = default;

    sparse_table(const std::vector<Band> &a) : n(a.size()) {
        table = std::vector(std::__lg(n) + 1, std::vector<Band>(n));
        for (int i = 0; i < n; i++) {
            table[0][i] = a[i];
        }
        for (int k = 1; (1 << k) <= n; k++) {
            for (int i = 0; i + (1 << k) <= n; i++) {
                table[k][i] =
                    op(table[k - 1][i], table[k - 1][i + (1 << (k - 1))]);
            }
        }
    }

    void build(const std::vector<Band> &a) {
        n = (int)a.size();
        table = std::vector(std::__lg(n) + 1, std::vector<Band>(n));
        for (int i = 0; i < n; i++) {
            table[0][i] = a[i];
        }
        for (int k = 1; (1 << k) <= n; k++) {
            for (int i = 0; i + (1 << k) <= n; i++) {
                table[k][i] =
                    op(table[k - 1][i], table[k - 1][i + (1 << (k - 1))]);
            }
        }
    }

    // [l, r)
    Band fold(int l, int r) {
        int k = std::__lg(r - l);
        return op(table[k][l], table[k][r - (1 << k)]);
    }

  private:
    int n;
    std::vector<std::vector<Band>> table;
};

}  // namespace ebi
#line 6 "tree/lowest_common_ancestor.hpp"

namespace ebi {

namespace internal_lca {
std::pair<int, int> op(std::pair<int, int> a, std::pair<int, int> b) {
    return a.second < b.second ? a : b;
}
}  // namespace internal_lca

struct lowest_common_ancestor {
  public:
    lowest_common_ancestor(const std::vector<std::vector<int>> &gh,
                           int root = 0)
        : n(gh.size()), id(n), depth(n) {
        auto dfs = [&](auto &&self, int v, int par = -1, int d = 0) -> void {
            id[v] = int(vs.size());
            depth[v] = d;
            vs.emplace_back(v, d);
            for (const auto &nv : gh[v])
                if (nv != par) {
                    self(self, nv, v, d + 1);
                    vs.emplace_back(v, d);
                }
        };
        dfs(dfs, root);
        st.build(vs);
    }

    int lca(int u, int v) {
        int l = id[u], r = id[v];
        if (r < l) std::swap(l, r);
        return st.fold(l, r + 1).first;
    }

    int distance(int u, int v) {
        int w = lca(u, v);
        return depth[u] + depth[v] - 2 * depth[w];
    }

  private:
    int n;
    std::vector<int> id, depth;
    std::vector<std::pair<int, int>> vs;
    sparse_table<std::pair<int, int>, internal_lca::op> st;
};

}  // namespace ebi
#line 2 "tree/level_ancestor.hpp"

#line 6 "tree/level_ancestor.hpp"

namespace ebi {

struct level_ancestor {
  private:
    int n;
    std::vector<int> in;
    std::vector<int> inv_in;
    std::vector<int> depths;
    std::vector<std::vector<int>> s;

  public:
    level_ancestor(const std::vector<std::vector<int>> &gh, int root = 0)
        : n(gh.size()), in(n), inv_in(n), depths(n) {
        int cnt = 0;
        int max = 0;
        auto dfs = [&](auto &&self, int v, int par = -1) -> void {
            inv_in[cnt] = v;
            in[v] = cnt++;
            max = std::max(max, depths[v]);
            for (auto nv : gh[v])
                if (nv != par) {
                    depths[nv] = depths[v] + 1;
                    self(self, nv, v);
                }
        };
        dfs(dfs, root);
        s.resize(max + 1);
        for (int i = 0; i < n; i++) {
            int u = inv_in[i];
            s[depths[u]].emplace_back(i);
        }
    }

    int query(int u, int k) const {
        int m = depths[u] - k;
        assert(m >= 0);
        return inv_in[*std::prev(
            std::upper_bound(s[m].begin(), s[m].end(), in[u]))];
    }

    int depth(int u) const {
        return depths[u];
    }
};

}  // namespace ebi
#line 192 "a.cpp"

namespace ebi {

void main_() {
    int n,q;
    std::cin >> n >> q;
    graph g(n);
    rep(i,0,n-1) {
        int a,b;
        std::cin >> a >> b;
        a--; b--;
        g.add_edge(a, b);
    }
    lowest_common_ancestor lca(g);
    level_ancestor la(g);
    std::vector<std::map<int,int>> dp(n);
    std::vector<int> sz(n, 1);
    auto dfs = [&](auto &&self, int v, int par = -1) -> void {
        for(auto nv: g[v]) {
            if(nv == par) continue;
            self(self, nv, v);
            sz[v] += sz[nv];
        }
    };
    std::vector<int> sum(n, 1);
    auto rerooting = [&](auto &&self, int v, int par = -1, int val = -1) -> void {
        if(par != -1) {
            dp[v][par] = val;
            sum[v] += val;
        }
        for(auto nv: g[v]) {
            if(nv == par) continue;
            self(self, nv, v, n - sz[nv]);
            dp[v][nv] = sz[nv];
            sum[v] += sz[nv];
        }
    };
    dfs(dfs, 0);
    rerooting(rerooting, 0);
    while(q--) {
        int s,t;
        std::cin >> s >> t;
        s--; t--;
        int d = lca.distance(s, t);
        if(d % 2 == 1) {
            std::cout << "0\n";
        }
        else {
            auto jump_k = [&](int s, int t, int k) -> int {
                int m = lca.lca(s, t);
                int d = lca.distance(s, t);
                if(d < k) return -1;
                int v;
                if(k <= lca.distance(s, m)) {
                    v = la.query(s, k);
                }
                else {
                    k = d - k;
                    assert(k <= lca.distance(m, t));
                    v = la.query(t, k);
                }
                return v;
            };
            int mid = jump_k(s, t, d/2);
            int l = jump_k(s, t, d/2 - 1);
            int r = jump_k(t, s, d/2 - 1);
            int ans = sum[mid] - dp[mid][l] - dp[mid][r];
            std::cout << ans << '\n';
        }
    }
}

}  // namespace ebi

int main() {
    std::cout << std::fixed << std::setprecision(15);
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    int t = 1;
    // std::cin >> t;
    while (t--) {
        ebi::main_();
    }
    return 0;
}
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