#90636 (C++11) No.274 The Wall

• 問題: No.274 The Wall
• ユーザー: codershifth
• 提出日時: 2016-05-07 15:15:21
• 言語: C++11 (gcc 13.3.0)
• 結果: AC
• 実行時間: 406 ms / 2,000 ms
• コード長: 3,556 bytes
• コンパイル時間: 1,642 ms
• コンパイル使用メモリ: 177,232 KB
• 実行使用メモリ: 131,968 KB
• 最終ジャッジ日時: 2024-06-22 02:09:00
• 合計ジャッジ時間: 3,343 ms
• ジャッジサーバーID （参考情報）: judge1 / judge2

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 <bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
#define FOR(i,a,b) for(int (i)=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define RANGE(vec) (vec).begin(),(vec).end()
using namespace std;
class SCC {
public:
    // for input or output data
    std::vector<std::vector<int>> G_;
    std::vector<int> cmp_;
    // for algorithm
    std::vector<std::vector<int>> rG_;
    std::vector<int> vs_;
    std::vector<bool> used_;
    SCC() {}
    SCC(int V) { init(V); }
    void init(int V) {
        G_.resize(V);
        rG_.resize(V);
        used_.resize(V);
        cmp_.resize(V);
    }
    ~SCC() {}
    void add(int from, int to) {
        assert(0 <= from && from <  (int)G_.size());
        assert(0 <= to && to <  (int)rG_.size());
        G_[from].push_back(to);
        rG_[to].push_back(from);
    }
    void dfs(int v) {
        used_[v] = true;
        for (int i = 0; i < (int)G_[v].size(); ++i)
        {
            if (!used_[G_[v][i]])
                dfs(G_[v][i]);
        }
        vs_.push_back(v);
    }
    void rdfs(int v, int k) {
        used_[v] = true;
        cmp_[v] = k;
        for (int i = 0; i < (int)rG_[v].size(); ++i)
        {
            if (!used_[rG_[v][i]])
                rdfs(rG_[v][i], k);
        }
    }
    //
    // O(|V|+|E|)
    //
    int decompose() {
        int V = G_.size();
        std::fill(used_.begin(), used_.end(), false);
        vs_.clear();
        for (int v = 0; v < V; ++v)
            if (!used_[v])
                dfs(v);
        std::fill(used_.begin(), used_.end(), false);
        int k = 0;
        for (int i = vs_.size()-1; i >= 0; i--)
            if (!used_[vs_[i]])
                rdfs(vs_[i], k++);
        return k;
    }
    const std::vector<int> &components() const {
        return cmp_;
    }
};
bool rangeIsCross(int s1, int e1, int s2, int e2)
{
    return max(s1,s2) <= min(e1,e2);
}
class TheWall
{
public:
    bool rangeIsCross(const pair<int,int> &a,
                      const pair<int,int> &b)
    {
        return ::rangeIsCross(a.first, a.second, b.first, b.second);
    }
    void solve(void)
    {
        int N,M;
        cin>>N>>M;
        vector<pair<int,int>> blks;
        REP(i,N)
        {
            int l,r;
            cin>>l>>r;
            blks.emplace_back(l,r);
        }
        SCC scc(N*2);
#define flip(BLK) make_pair(M-1-(BLK).second, M-1-(BLK).first)
        REP(i,N)
        {
            // 対偶も追加
#define Add(X,Y) do { scc.add(X,Y); scc.add((Y+N)%(2*N), (X+N)%(2*N));} while(0)
            REP(j,i)
            {
                // 交差しないときに辺を張るのではなくて、
                // 交差するときにそれを回避するための制約として辺を張る
                if (rangeIsCross(blks[i], blks[j]))
                    Add(i,j+N);
                if (rangeIsCross(blks[i],flip(blks[j])))
                    Add(i,j);
                if (rangeIsCross(flip(blks[i]),blks[j]))
                    Add(i+N,j+N);
                if (rangeIsCross(flip(blks[i]),flip(blks[j])))
                    Add(i+N,j);
            }
        }
        scc.decompose();
        REP(i,N)
        {
            if ( scc.cmp_[i] == scc.cmp_[i+N] )
            {
                cout<<"NO"<<endl;
                return;
            }
        }
        cout<<"YES"<<endl;
    }
};
#if 1
int main(int argc, char *argv[])
{
        ios::sync_with_stdio(false);
        auto obj = new TheWall();
        obj->solve();
        delete obj;
        return 0;
}
#endif
 
 
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