結果

問題 No.2337 Equidistant
ユーザー dyktr_06dyktr_06
提出日時 2023-06-02 23:29:47
言語 C++17
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 1,059 ms / 4,000 ms
コード長 8,830 bytes
コンパイル時間 5,506 ms
コンパイル使用メモリ 286,292 KB
実行使用メモリ 86,920 KB
最終ジャッジ日時 2024-06-09 01:40:55
合計ジャッジ時間 21,538 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge3
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
6,816 KB
testcase_01 AC 2 ms
6,944 KB
testcase_02 AC 2 ms
6,940 KB
testcase_03 AC 2 ms
6,940 KB
testcase_04 AC 2 ms
6,944 KB
testcase_05 AC 2 ms
6,944 KB
testcase_06 AC 5 ms
6,940 KB
testcase_07 AC 5 ms
6,944 KB
testcase_08 AC 5 ms
6,944 KB
testcase_09 AC 5 ms
6,944 KB
testcase_10 AC 6 ms
6,944 KB
testcase_11 AC 730 ms
75,728 KB
testcase_12 AC 751 ms
75,748 KB
testcase_13 AC 757 ms
75,772 KB
testcase_14 AC 772 ms
75,912 KB
testcase_15 AC 773 ms
75,756 KB
testcase_16 AC 723 ms
75,940 KB
testcase_17 AC 734 ms
75,824 KB
testcase_18 AC 738 ms
75,768 KB
testcase_19 AC 751 ms
75,852 KB
testcase_20 AC 735 ms
75,932 KB
testcase_21 AC 569 ms
86,920 KB
testcase_22 AC 1,059 ms
76,668 KB
testcase_23 AC 675 ms
77,400 KB
testcase_24 AC 871 ms
82,712 KB
testcase_25 AC 685 ms
77,360 KB
testcase_26 AC 957 ms
82,620 KB
testcase_27 AC 719 ms
77,312 KB
testcase_28 AC 714 ms
77,392 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>
#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();
}
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