結果

問題 No.2464 To DAG
コンテスト
ユーザー MMRZ
提出日時 2023-09-08 23:18:30
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 6,632 bytes
コンパイル時間 4,168 ms
コンパイル使用メモリ 279,964 KB
実行使用メモリ 295,888 KB
最終ジャッジ日時 2024-06-26 16:42:13
合計ジャッジ時間 9,133 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample WA * 2
other TLE * 1 -- * 38
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;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T hinf() { return inf<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); }
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); }
template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; }
template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; }
template<class T> bool is_sqare(T a) { if(floor(sqrt(a)) * floor(sqrt(a)) == a){ return true; }return false; }
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); };
ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; };
template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>;
# define all(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        sort(all((wpwpw)));(wpwpw).erase(unique(all((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(all((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(all((rprpr)),(rprpr).begin(),TU<char>)
# define rep(i,upupu)         for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++)
# define reps(i,opopo)        for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++)
# define len(x)                ((int)(x).size())
# define bit(n)               (1LL << (n))
# define pb push_back
#ifdef LOCAL
#  include "_debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

struct INIT{
    INIT(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(0);
        cout << fixed << setprecision(20);
    }
}INIT;

class FindingAllCycles {
private:
    struct node {
        int prev, next, to;
        node(const int _prev, const int _next, const int _to)
            : prev(_prev), next(_next), to(_to){}
    };
    const int V;
    vector<vector<node> > G;
    vector<stack<int> > block_stack;
    stack<int> st;
    bool *fix, *blocked, *used;
    bool enumerate;
    void erase_edge(const int u, const int id){
        G[u][G[u][id].next].prev = G[u][id].prev;
        G[u][G[u][id].prev].next = G[u][id].next;
    }
    void scc_dfs(const int u, int& tm, int& cnt,
            vector<int>& ord, vector<int>& low, vector<int>& cmp, stack<int>& st){
        ord[u] = low[u] = tm++, st.push(u);
        for(int id = G[u][0].next; id != 0; id = G[u][id].next){
            const int v = G[u][id].to;
            if(ord[v] < 0){
                scc_dfs(v, tm, cnt, ord, low, cmp, st);
                low[u] = min(low[u], low[v]);
            }else if(cmp[v] < 0){
                low[u] = min(low[u], ord[v]);
            }
            if(cmp[v] >= 0) erase_edge(u, id);
        }
        if(ord[u] == low[u]){
            while(true){
                const int v = st.top();
                st.pop(), cmp[v] = cnt;
                if(v == u) break;
            }
            ++cnt;
        }
    }
    void scc(){
        vector<int> ord(V, -1), low(V), cmp(V, -1);
        stack<int> st;
        int tm = 0, cnt = 0;
        for(int i = 0; i < V; ++i){
            if(ord[i] < 0) scc_dfs(i, tm, cnt, ord, low, cmp, st);
        }
    }
    void unblock(const int u){
        blocked[u] = false;
        while(!block_stack[u].empty()){
            const int v = block_stack[u].top();
            block_stack[u].pop();
            if(blocked[v]) unblock(v);
        }
    }
    bool dfs(const int u, const int s, vector<int>& path, vector<int>& ver_list){
        bool flag = false;
        path.push_back(u);
        blocked[u] = true;
        if(!used[u]) used[u] = true, ver_list.push_back(u);
        for(int id = G[u][0].next; id != 0; id = G[u][id].next){
            const int v = G[u][id].to;
            if(fix[v]){
                erase_edge(u, id);
                continue;
            }
            if(v == s){
                if(enumerate) ans.push_back(path);
                ++count, flag = true;
            }else if(!blocked[v]){
                if(dfs(v, s, path, ver_list)) flag = true;
            }
        }
        if(flag) unblock(u);
        else{
            for(int id = G[u][0].next; id != 0; id = G[u][id].next){
                block_stack[G[u][id].to].push(u);
            }
        }
        path.pop_back();
        return flag;
    }
 
public:
    vector<vector<int>> ans;
    int count;
    FindingAllCycles(const int node_size)
        : V(node_size), G(V, vector<node>{{0, 0, -1}}), block_stack(V),
            fix(new bool[V]()), blocked(new bool[V]()), used(new bool[V]()), count(0){}
    ~FindingAllCycles(){
        delete[] fix, delete[] blocked, delete[] used;
    }
    void add_edge(const int u, const int v){
        if(u == v){
            ans.push_back({u});
            return;
        }
        G[u][0].prev = G[u].back().next = (int)G[u].size();
        G[u].push_back((node){(int)G[u].size() - 1, 0, v});
    }
    int solve(bool _enumerate=true){
        scc();
        enumerate = _enumerate;
        for(int i = 0; i < V; ++i){
            vector<int> path, ver_list;
            dfs(i, i, path, ver_list);
            fix[i] = true;
            for(int j : ver_list){
                used[j] = blocked[j] = false, block_stack[j] = stack<int>();
            }
        }
        return count;
    }
};

void solve(){
    int n, m;
    cin >> n >> m;
    vector<vector<int>> g(n);
    vector<int> u(m), v(m);
    FindingAllCycles fc(n);
    rep(i, m){
        cin >> u[i] >> v[i];
        u[i]--, v[i]--;
        g[u[i]].push_back(v[i]);
        fc.add_edge(u[i], v[i]);
    }

    fc.solve(true);
    
    set<int> ban_v;

    set<pair<int, int>> ban;
    rep(i, len(fc.ans)){
        debug(fc.ans[i]);
        bool flg = false;
        for(auto x : fc.ans[i]){
            if(ban_v.count(x))flg = true;
        }
        if(flg)continue;
        rep(j, len(fc.ans[i])){
            ban.insert({fc.ans[i][j], fc.ans[i][(j + 1) % len(fc.ans)]});
            ban_v.insert(fc.ans[i][j]);
        }
    }


    rep(i, m){
        if(ban.count({u[i], v[i]}))continue;
        cout << u[i] + 1 << " " << v[i] + 1 << endl;
    }

}

int main(){
    int t = 1;
    //cin >> t;
    while(t--)solve();
}
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