結果

問題 No.2337 Equidistant
ユーザー Kyo_s_sKyo_s_s
提出日時 2023-06-02 22:53:30
言語 C++17
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 845 ms / 4,000 ms
コード長 9,652 bytes
コンパイル時間 2,814 ms
コンパイル使用メモリ 225,088 KB
実行使用メモリ 50,976 KB
最終ジャッジ日時 2024-06-09 00:41:55
合計ジャッジ時間 14,393 ms
ジャッジサーバーID
（参考情報） 		judge3 / 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 2 ms
5,376 KB
testcase_02 AC 2 ms
5,376 KB
testcase_03 AC 2 ms
5,376 KB
testcase_04 AC 2 ms
5,376 KB
testcase_05 AC 2 ms
5,376 KB
testcase_06 AC 3 ms
5,376 KB
testcase_07 AC 4 ms
5,376 KB
testcase_08 AC 3 ms
5,376 KB
testcase_09 AC 4 ms
5,376 KB
testcase_10 AC 3 ms
5,376 KB
testcase_11 AC 419 ms
33,456 KB
testcase_12 AC 405 ms
33,580 KB
testcase_13 AC 430 ms
33,584 KB
testcase_14 AC 463 ms
33,448 KB
testcase_15 AC 417 ms
33,588 KB
testcase_16 AC 398 ms
33,580 KB
testcase_17 AC 427 ms
33,584 KB
testcase_18 AC 421 ms
33,576 KB
testcase_19 AC 414 ms
33,452 KB
testcase_20 AC 429 ms
33,452 KB
testcase_21 AC 559 ms
50,976 KB
testcase_22 AC 353 ms
34,516 KB
testcase_23 AC 354 ms
34,844 KB
testcase_24 AC 716 ms
44,852 KB
testcase_25 AC 353 ms
34,840 KB
testcase_26 AC 845 ms
44,608 KB
testcase_27 AC 368 ms
34,716 KB
testcase_28 AC 385 ms
34,732 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 <bits/stdc++.h>
using namespace std;
// #include <atcoder/all>
// using namespace atcoder;

/* alias */
using ull = unsigned long long;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vll = vector<long long>;
using vd = vector<double>;
using vs = vector<string>;
using vb = vector<bool>;
using vpii = vector<pair<int, int>>;
using vpll = vector<pair<ll, ll>>;
using vvi = vector<vector<int>>;
using vvll = vector<vector<long long>>;
using vvd = vector<vector<double>>;
using vvs = vector<vector<string>>;
using vvb = vector<vector<bool>>;
template<typename T> using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;

/* define */
#define MOD 998244353
// #define MOD 1000000007
#define INF (1LL << 60)
#define elif else if
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define all(obj) (obj).begin(), (obj).end()
#define YESNO(bool) cout << (bool ? "YES\n" : "NO\n")
#define YesNo(bool) cout << (bool ? "Yes\n" : "No\n")
#define yesno(bool) cout << (bool ? "yes\n" : "no\n")
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;}
#define debug(x) cerr << #x << ":" << x << "\n";

/* REP macro */
#define reps(i, a, n) for(ll i = (a); i < (n); i++)
#define rep(i, n) reps(i, 0, (n))
#define rrep(i, n) reps(i, 1, (n + 1))
#define repd(i, n) for(ll i = (n - 1); i >= 0; i--)
#define rrepd(i, n) for(ll i = (n); i >= 1; i--)
#define fore(i, a) for(auto &i: a)

/* vector */
template<class T> T vmax(vector<T> &array){ T ret = array[0]; for(T a: array) chmax(ret, a); return ret; }
template<class T> T vmin(vector<T> &array){ T ret = array[0]; for(T a: array) chmin(ret, a); return ret; }
template<class T> T sum(vector<T> &array){ T ret = 0; for(T a:array) ret += a; return ret; }
template<class T> void list_set(vector<T> &array){ sort(all(array)); array.erase(unique(all(array)),array.end()); }
template<class T> int bisect_left(vector<T> &array, T key){ return lower_bound(all(array),key) - array.begin(); }
template<class T> int bisect_right(vector<T> &array, T key){ return upper_bound(all(array),key) - array.begin(); }

/* string */
ll string_to_ll(string n){ ll ret = 0, k = 1; while(n.length() > 0){ ret += k * (n.back() - '0'); n.pop_back(); k *= 10; } return ret; }
string ll_to_string(ll n){ string ret = ""; while(n > 0){ ret.pb((n % 10) + '0'); n /= 10; } reverse(all(ret)); return ret; }

struct popopo{ popopo(){ cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(15); }; } popopoppo;

// n = 1,...,N に対して、n % A < B を満たすものの数 
ll Count_of_n_mod_A_less_than_B(ll N, ll A, ll B){ return N / A * min(A, B) + min(N % A, B - 1); }

bool include(ll l, ll r, ll x) { return l <= x && x < r; }

/* IN/OUT */
int scan() { return getchar(); }
void scan(int &a) { cin >> a; }
void scan(long long &a) { cin >> a; }
void scan(char &a) { cin >> a; }
void scan(double &a) { cin >> a; }
void scan(string &a) { cin >> a; }
template <class T, class S> void scan(pair<T, S> &p) { scan(p.first), scan(p.second); }
template <class T> void scan(vector<T> &);
template <class T> void scan(vector<T> &a) { for(auto &i : a) scan(i); }

void IN(){}
template<class Head, class... Tail> void IN(Head& head, Tail &...tail){ scan(head); IN(tail...); }

#define INT(...) int __VA_ARGS__; IN(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__; IN(__VA_ARGS__)
#define STR(...) string __VA_ARGS__; IN(__VA_ARGS__)
#define VEC(type, name, size) vector<type> name(size); IN(name)
#define VECS(type, name, size) vector<type> name(size + 1); for(int i = 1; i <= size; i++) scan(name[i])

void OUT(){ cout << "\n"; }
template<class T> void output(T a){ cout << a; }
template<class T> void output(vector<T> v){ for(int i = 0; i < v.size(); i++) cout << v[i] << (i == v.size() - 1 ? "" : " "); }
template<class Head, class... Tail> void OUT(const Head &head, const Tail &...tail) { output(head); if(sizeof...(tail)) cout << " "; OUT(tail...); }

void FLASH(){ cout << endl; }
template<class Head, class... Tail> void FLASH(const Head  &head, const Tail &...tail) { output(head); if(sizeof...(tail)) cout << " "; FLASH(tail...); }

namespace kyo {

long long bisect(long long ok, long long ng, function<bool(long long)> is_ok) { while (abs(ok - ng) > 1) { long long mid = ok + (ng - ok) / 2; (is_ok(mid) ? ok : ng) = mid; } return ok; }

}


template<class T = int> struct Tree {
    struct edge{ int to; T cost; };
    vector<vector<edge>> G;
    vector<vector<int>> parent;
    vector<int> unweighted_dist;
    vector<T> weighted_dist;

    Tree(int n) : G(n) {}

    void add_edge(int u, int v) { add_edge(u, v, T(1)); }
    void add_edge(int u, int v, T w) {
        G[u].push_back({v, w});
        G[v].push_back({u, w});
    }

    vector<int> get_count(int root = 0) {
        vector<int> count(G.size(), 0);
        function<void(int, int)> dfs = [&](int v, int p) {
            count[v] = 1;
            for (auto e: G[v]) {
                if (e.to == p) continue;
                dfs(e.to, v);
                count[v] += count[e.to];
            }
        };
        dfs(root, -1);

        return count;
    }


    vector<T> calc_dist(int root = 0) {
        vector<T> dist(G.size(), -1); dist[root] = 0;
        queue<int> que; que.push(root);
        while (!que.empty()) {
            int v = que.front(); que.pop();
            for (auto e: G[v]) {
                if (dist[e.to] != -1) continue;
                dist[e.to] = dist[v] + e.cost;
                que.push(e.to);
            }
        }
        return dist;
    }

    tuple<T, int, int> diameter() {
        vector<T> dist = calc_dist();
        int v = max_element(dist.begin(), dist.end()) - dist.begin();
        dist = calc_dist(v);
        int u = max_element(dist.begin(), dist.end()) - dist.begin();
        return { dist[u], u, v };
    }

    vector<int> path(int u, int v) {
        vector<T> dist = calc_dist(u);
        vector<int> path;
        while (v != u) {
            path.push_back(v);
            for (auto e: G[v]) {
                if (dist[e.to] == dist[v] - e.cost) {
                    v = e.to;
                    break;
                }
            }
        }
        path.push_back(u);
        reverse(path.begin(), path.end());
        return path;
    }

    void lca_build(int root = 0) {
        int V = G.size();
        int K = 1;
        while ((1 << K) < V) K++;
        parent.assign(K, vector<int>(V, -1));
        unweighted_dist.assign(V, -1);

        auto unweighted_dfs = [this](auto&& self, int v, int p, int d) -> void {
            parent[0][v] = p;
            unweighted_dist[v] = d;
            for (auto e: G[v]) {
                if (e.to == p) continue;
                self(self, e.to, v, d + 1);
            }
        };

        unweighted_dfs(unweighted_dfs, 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]];
            }
        }

        weighted_dist.assign(V, -1); weighted_dist[root] = 0;
        queue<int> que; que.push(root);
        while (!que.empty()) {
            int v = que.front(); que.pop();
            for (auto e: G[v]) {
                if (weighted_dist[e.to] == -1 || weighted_dist[e.to] > weighted_dist[v] + e.cost) {
                    weighted_dist[e.to] = weighted_dist[v] + e.cost;
                    que.push(e.to);
                }
            }
        }
    }

    int lca(int u, int v) {
        if (parent.size() == 0) lca_build();
        if (unweighted_dist[u] < unweighted_dist[v]) swap(u, v);
        int K = parent.size();
        for (int k = 0; k < K; k++) {
            if ((unweighted_dist[u] - unweighted_dist[v]) >> k & 1) {
                u = parent[k][u];
            }
        }
        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 prev(int u, int x) {
        // 頂点 u から x 個親へ
        if (parent.size() == 0) lca_build();
        int K = parent.size();
        for (int k = 0; k < K; k++) {
            if ((x >> k) & 1) {
                u = parent[k][u];
            }
        }
        return u;
    }

    T dist(int u, int v) {
        if (weighted_dist.size() == 0) lca_build();
        return weighted_dist[u] + weighted_dist[v] - 2 * weighted_dist[lca(u, v)];
    }
};

    




    
int main() {

    LL(N, Q);
    Tree tree(N);
    vll out(N, 0);
    rep(i, N - 1) {
        LL(A, B);
        tree.add_edge(A - 1, B - 1);
        out[A - 1]++;
        out[B - 1]++;
    }

    auto count = tree.get_count();

    while (Q--) {
        LL(s, t); s--; t--;

        ll dist = tree.dist(s, t);
        if (dist % 2 != 0) {
            OUT(0);
            continue;
        }

        ll lca = tree.lca(s, t);
        if (tree.dist(lca, s) < tree.dist(lca, t)) swap(s, t);

        // s から dist / 2 個前の親
        ll d = dist / 2;
        ll c = tree.prev(s, d);
        

        // c から出るs, t に行かない頂点の数
        ll ans;  
        if (lca != c) {
            // tree.prev(s, d - 1) が c の子
            ans = count[c] - count[tree.prev(s, d - 1)];
        } else {
            ans = N - count[tree.prev(s, d - 1)] - count[tree.prev(t, d - 1)];
        }
        OUT(ans);
    }





}
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