test/yukicoder/yuki_1326_2.test.cpp

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Last update: 2022-07-24 02:46:13+09:00
Problem: https://yukicoder.me/problems/no/1326

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Code

#define PROBLEM "https://yukicoder.me/problems/no/1326"
#include <bits/stdc++.h>
using namespace std;
#include "../../graph/extended_block_cut_tree.hpp"
#include "../../data_structure/tree/heavy_light_decomposition.hpp"
int main(){
  int N, M;
  cin >> N >> M;
  vector<vector<int>> E(N);
  for (int i = 0; i < M; i++){
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    E[a].push_back(b);
    E[b].push_back(a);
  }
  extended_block_cut_tree T(E);
  int V = T.size();
  vector<int> p(V, -1);
  vector<vector<int>> c(V);
  vector<int> d(V, 0);
  queue<int> q;
  q.push(0);
  while (!q.empty()){
    int v = q.front();
    q.pop();
    for (int w : T[v]){
      if (w != p[v]){
        p[w] = v;
        c[v].push_back(w);
        d[w] = d[v] + 1;
        q.push(w);
      }
    }
  }
  heavy_light_decomposition HLD(p, c);
  int Q;
  cin >> Q;
  for (int i = 0; i < Q; i++){
    int x, y;
    cin >> x >> y;
    x--;
    y--;
    cout << max(HLD.dist(x, y) / 2 - 1, 0) << endl;
  }
}

#line 1 "test/yukicoder/yuki_1326_2.test.cpp"
#define PROBLEM "https://yukicoder.me/problems/no/1326"
#include <bits/stdc++.h>
using namespace std;
#line 2 "graph/extended_block_cut_tree.hpp"
/**
 * @brief 拡張 Block Cut Tree
*/
struct extended_block_cut_tree{
  int N, cnt;
  vector<vector<int>> G;
  extended_block_cut_tree(vector<vector<int>> &E){
    N = E.size();
    vector<int> next(N, -1);
    vector<int> d(N, -1);
    vector<int> imos(N, 0);
    for (int i = 0; i < N; i++){
      if (d[i] == -1){
        d[i] = 0;
        dfs1(E, next, d, imos, i);
      }
    }
    cnt = 0;
    G.resize(N + 1);
    vector<bool> used(N, false);
    for (int i = 0; i < N; i++){
      if (d[i] == 0){
        dfs2(E, d, imos, used, cnt, i);
      }
      if (E[i].empty()){
        G[i].push_back(N + cnt);
        G[N + cnt].push_back(i);
        cnt++;
        G.push_back({});
      }
    }
    G.pop_back();
  }
  void dfs1(vector<vector<int>> &E, vector<int> &next, vector<int> &d, vector<int> &imos, int v){
    for (int w : E[v]){
      if (d[w] == -1){
        d[w] = d[v] + 1;
        next[v] = w;
        dfs1(E, next, d, imos, w);
        imos[v] += imos[w];
      } else if (d[w] < d[v] - 1){
        imos[v]++;
        imos[next[w]]--;
      }
    }
  }
  void dfs2(vector<vector<int>> &E, vector<int> &d, vector<int> &imos, vector<bool> &used, int b, int v){
    used[v] = true;
    bool ok = false;
    for (int w : E[v]){
      if (d[w] == d[v] + 1 && !used[w]){
        if (imos[w] > 0){
          if (!ok){
            ok = true;
            G[v].push_back(N + b);
            G[N + b].push_back(v);
          }
          dfs2(E, d, imos, used, b, w);
        } else {
          G[v].push_back(N + cnt);
          G[N + cnt].push_back(v);
          cnt++;
          G.push_back({});
          dfs2(E, d, imos, used, cnt - 1, w);
        }
      }
    }
    if (!ok && d[v] > 0){
      G[v].push_back(N + b);
      G[N + b].push_back(v);
    }
  }
  int size(){
    return G.size();
  }
  vector<int> &operator [](int v){
    return G[v];
  }
};
#line 2 "data_structure/tree/heavy_light_decomposition.hpp"
/**
 * @brief 重軽分解
*/
struct heavy_light_decomposition{
  vector<int> p, sz, in, next;
  void dfs1(vector<vector<int>> &c, int v){
    sz[v] = 1;
    for (int &w : c[v]){
      dfs1(c, w);
      sz[v] += sz[w];
      if (sz[w] > sz[c[v][0]]){
        swap(w, c[v][0]);
      }
    }
  }
  void dfs2(vector<vector<int>> &c, int &t, int v){
    in[v] = t;
    t++;
    for (int w : c[v]){
      if (w == c[v][0]){
        next[w] = next[v];
      } else {
        next[w] = w;
      }
      dfs2(c, t, w);
    }
  }
  heavy_light_decomposition(vector<int> &p, vector<vector<int>> &c, int r = 0): p(p){
    int N = p.size();
    sz = vector<int>(N);
    dfs1(c, r);
    in = vector<int>(N);
    next = vector<int>(N, r);
    int t = 0;
    dfs2(c, t, r);
  }
  int lca(int u, int v){
    while (true){
      if (in[u] > in[v]){
        swap(u, v);
      }
      if (next[u] == next[v]){
        return u;
      }
      v = p[next[v]];
    }
  }
  int dist(int u, int v){
    int ans = 0;
    while (true){
      if (in[u] > in[v]){
        swap(u, v);
      }
      if (next[u] == next[v]){
        ans += in[v] - in[u];
        return ans;
      }
      ans += in[v] - in[next[v]] + 1;
      v = p[next[v]];
    }
  }
};
#line 6 "test/yukicoder/yuki_1326_2.test.cpp"
int main(){
  int N, M;
  cin >> N >> M;
  vector<vector<int>> E(N);
  for (int i = 0; i < M; i++){
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    E[a].push_back(b);
    E[b].push_back(a);
  }
  extended_block_cut_tree T(E);
  int V = T.size();
  vector<int> p(V, -1);
  vector<vector<int>> c(V);
  vector<int> d(V, 0);
  queue<int> q;
  q.push(0);
  while (!q.empty()){
    int v = q.front();
    q.pop();
    for (int w : T[v]){
      if (w != p[v]){
        p[w] = v;
        c[v].push_back(w);
        d[w] = d[v] + 1;
        q.push(w);
      }
    }
  }
  heavy_light_decomposition HLD(p, c);
  int Q;
  cin >> Q;
  for (int i = 0; i < Q; i++){
    int x, y;
    cin >> x >> y;
    x--;
    y--;
    cout << max(HLD.dist(x, y) / 2 - 1, 0) << endl;
  }
}