結果

問題 No.274 The Wall
ユーザー pione
提出日時 2021-03-12 00:11:10
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 508 ms / 2,000 ms
コード長 2,889 bytes
コンパイル時間 2,770 ms
コンパイル使用メモリ 215,964 KB
実行使用メモリ 194,944 KB
最終ジャッジ日時 2025-03-17 19:09:32
合計ジャッジ時間 5,291 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
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ファイルパターン 結果
sample AC * 4
other AC * 23
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;

struct StronglyConnectedComponents {
  int n;
  vector<vector<int>> G, rG;
  vector<int> order, component;
  vector<bool> used;
  void dfs(int v) {
    used[v] = 1;
    for (auto nv : G[v]) {
      if (!used[nv]) dfs(nv);
    }
    order.push_back(v);
  }
  void rdfs(int v, int k) {
    component[v] = k;
    for (auto nv : rG[v]) {
      if (component[nv] < 0) rdfs(nv, k);
    }
  }

  StronglyConnectedComponents(vector<vector<int>> &_G) {
    n = _G.size();
    G = _G;
    rG.resize(n);
    component.assign(n, -1);
    used.resize(n);
    for (int v = 0; v < n; v++) {
      for (auto nv : G[v]) rG[nv].push_back(v);
    }
    for (int v = 0; v < n; v++) if (!used[v]) dfs(v);
    int k = 0;
    reverse(order.begin(), order.end());
    for (auto v : order) if (component[v] == -1) rdfs(v, k), k++;
  }

  bool is_same(int u, int v) { return component[u] == component[v]; }

  vector<vector<int>> rebuild() {
    int N = *max_element(component.begin(), component.end()) + 1;
    vector<vector<int>> rebuildedG(N);
    set<pair<int, int>> connected;
    for (int v = 0; v < N; v++) {
      for (auto nv : G[v]) {
        if (component[v] != component[nv] and !connected.count(pair(v, nv))) {
          connected.insert(pair(v, nv));
          rebuildedG[component[v]].push_back(component[nv]);
        }
      }
    }
    return rebuildedG;
  }
};

#define rep(i, n) for (long long i = (long long)(0); i < (long long)(n); ++i)
#define irep(i, m, n) for (long long i = (long long)(m); i < (long long)(n); ++i)
using ll = long long;
template<class t> using vc=vector<t>;

signed main()
{
  cin.tie( 0 ); ios::sync_with_stdio( false );
  
  int n,m; cin>>n>>m;
  vc<int> l(n), r(n);
  rep(i,n) cin>>l[i]>>r[i];
  
  vc<vc<int>> G(2*n);
  rep(i,n){
    irep(j,i+1,n){
      int l1=l[i], r1=r[i], l2=l[j], r2=r[j];
      int L1=m-r1-1, R1=m-l1-1, L2=m-r2-1, R2=m-l2-1;
      if(l1<=l2 and l2<=r1 or l1<=r2 and r2<=r1
        or l2<=l1 and l1<=r2){
        // A∨B <=> ￢A=>B∧￢B=>A
        G[i+n].push_back(j);
        G[j+n].push_back(i);
      }
      if(l1<=L2 and L2<=r1 or l1<=R2 and R2<=r1
        or L2<=l1 and l1<=R2){
        // A∨￢B <=> ￢A=>￢B∧B=>A
        G[i+n].push_back(j+n);
        G[j].push_back(i);
      }
      if(L1<=l2 and l2<=R1 or L1<=r2 and r2<=R1
        or l2<=L1 and L1<=r2){
        // ￢A∨B <=> A=>B∧￢B=>￢A
        G[i].push_back(j);
        G[j+n].push_back(i+n);
      }
      if(L1<=L2 and L2<=R1 or L1<=R2 and R2<=R1
        or L2<=L1 and L1<=R2){
        // ￢A∨￢B <=> A=>￢B∧B=>￢A
        G[i].push_back(j+n);
        G[j].push_back(i+n);
      }
    }
  }
  
  auto scc = StronglyConnectedComponents(G);
  rep(i,n){
    if(scc.is_same(i,i+n)){
      cout<<"NO"<<endl;
      return 0;
    }
  }
  cout<<"YES"<<endl;
}
0