#173951 (C++14) No.274 The Wall

• 問題: No.274 The Wall
• ユーザー: 193s
• 提出日時: 2017-05-17 17:55:33
• 言語: C++14 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 518 ms / 2,000 ms
• コード長: 1,974 bytes
• コンパイル時間: 1,135 ms
• コンパイル使用メモリ: 92,472 KB
• 実行使用メモリ: 132,224 KB
• 最終ジャッジ日時: 2024-06-22 02:17:10
• 合計ジャッジ時間: 3,529 ms
• ジャッジサーバーID （参考情報）: judge2 / judge5

ファイルパターン	結果
sample	AC * 4
other	AC * 22

ソースコード

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#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cmath>
using namespace std;
typedef pair<int, int> P;
#define rep(i, n) for (int i=0; i<(n); i++)
#define all(c) (c).begin(), (c).end()
#define uniq(c) c.erase(unique(all(c)), (c).end())
#define _1 first
#define _2 second
#define pb push_back
#define INF 1145141919
#define MOD 1000000007
int N, M;
int L[4000], R[4000];
vector<int> vs;
class SAT2 {
public:
  int N;
  vector< vector<int> > G, R;
  vector<int> vs, used, ord;
  SAT2 (int N) : N(N) {
    G.resize(2*N);
    R.resize(2*N);
    used.resize(2*N);
    ord.resize(2*N);
  }
  void add_edge(int x, int y) {
    G[x].pb(y);
    R[y].pb(x);
  }
  void dfs(int x) {
    if (used[x]) return;
    used[x] = true;
    for (int t : G[x]) dfs(t);
    vs.pb(x);
  }
  void rdfs(int x, int k) {
    if (used[x]) return;
    used[x] = true;
    ord[x] = k;
    for (int t : R[x]) rdfs(t, k);
  }
  int scc() {
    rep(i, 2*N) used[i] = false;
    rep(i, 2*N) dfs(i);
    rep(i, 2*N) used[i] = false;
    int k = 0;
    for (int i=vs.size()-1; i>=0; i--) {
      if (!used[vs[i]]) rdfs(vs[i], k++);
    }
    return k;
  }
  bool is_sat() {
    scc();
    rep(i, N) {
      if (ord[i] == ord[i+N]) return false;
    }
    return true;
  }
};
signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  cin >> N >> M;
  rep(i, N) {
    cin >> L[i] >> R[i];
    L[i+N] = M-1-R[i];
    R[i+N] = M-1-L[i];
  }
  SAT2 sat(N);
  for (int x=0; x<2*N; x++) {
    for (int y=x+1; y<2*N; y++) {
      if (x % N == y % N) continue;
      if (max(L[x], L[y]) > min(R[x], R[y])) continue;
      // (not x) | (not y)
      // x => not y, y => not x
      //cout<<(x>=N?"!":"")<<(x%N)<<"<->"<<(y>=N?"!":"")<<(y%N)<<"\n";
      sat.add_edge(x, (y+N)%(2*N));
      sat.add_edge(y, (x+N)%(2*N));
    }
  }
  if (sat.is_sat()) cout << "YES\n";
  else cout << "NO\n";
  return 0;
}
 
 
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