結果

問題 No.1553 Lovely City
ユーザー 👑 tute7627tute7627
提出日時 2021-06-18 21:50:47
言語 C++17
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 161 ms / 2,000 ms
コード長 8,612 bytes
コンパイル時間 3,136 ms
コンパイル使用メモリ 228,636 KB
実行使用メモリ 29,328 KB
最終ジャッジ日時 2024-06-22 20:14:24
合計ジャッジ時間 10,219 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge5
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
5,248 KB
testcase_01 AC 2 ms
5,376 KB
testcase_02 AC 29 ms
24,320 KB
testcase_03 AC 2 ms
5,376 KB
testcase_04 AC 2 ms
5,376 KB
testcase_05 AC 2 ms
5,376 KB
testcase_06 AC 2 ms
5,376 KB
testcase_07 AC 2 ms
5,376 KB
testcase_08 AC 92 ms
18,824 KB
testcase_09 AC 106 ms
19,952 KB
testcase_10 AC 122 ms
23,300 KB
testcase_11 AC 79 ms
17,324 KB
testcase_12 AC 120 ms
27,460 KB
testcase_13 AC 88 ms
17,620 KB
testcase_14 AC 101 ms
18,980 KB
testcase_15 AC 89 ms
18,840 KB
testcase_16 AC 120 ms
20,612 KB
testcase_17 AC 93 ms
19,340 KB
testcase_18 AC 153 ms
29,204 KB
testcase_19 AC 161 ms
29,200 KB
testcase_20 AC 160 ms
29,200 KB
testcase_21 AC 154 ms
29,320 KB
testcase_22 AC 155 ms
29,200 KB
testcase_23 AC 144 ms
29,192 KB
testcase_24 AC 148 ms
29,328 KB
testcase_25 AC 152 ms
29,204 KB
testcase_26 AC 149 ms
29,324 KB
testcase_27 AC 153 ms
29,200 KB
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 # 

//#define _GLIBCXX_DEBUG

#include<bits/stdc++.h>
using namespace std;

#define endl '\n'
#define lfs cout<<fixed<<setprecision(10)
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i,n,m) for(ll i = (n); i < (ll)(m); i++)
#define rrep(i,n,m) for(ll i = (ll)(m) - 1; i >= (ll)(n); i--)
using ll = long long;
using ld = long double;
const ll MOD1 = 1e9+7;
const ll MOD9 = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
template<typename T> using PQ = priority_queue<T>;
template<typename T> using QP = priority_queue<T,vector<T>,greater<T>>;
template<typename T1, typename T2>bool chmin(T1 &a,T2 b){if(a>b){a=b;return true;}else return false;}
template<typename T1, typename T2>bool chmax(T1 &a,T2 b){if(a<b){a=b;return true;}else return false;}
ll median(ll a,ll b, ll c){return a+b+c-max({a,b,c})-min({a,b,c});}
void ans1(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}
void ans2(bool x){if(x) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
void ans3(bool x){if(x) cout<<"Yay!"<<endl;else cout<<":("<<endl;}
template<typename T1,typename T2>void ans(bool x,T1 y,T2 z){if(x)cout<<y<<endl;else cout<<z<<endl;}  
template<typename T1,typename T2,typename T3>void anss(T1 x,T2 y,T3 z){ans(x!=y,x,z);};  
template<typename T>void debug(const T &v,ll h,ll w,string sv=" "){for(ll i=0;i<h;i++){cout<<v[i][0];for(ll j=1;j<w;j++)cout<<sv<<v[i][j];cout<<endl;}};
template<typename T>void debug(const T &v,ll n,string sv=" "){if(n!=0)cout<<v[0];for(ll i=1;i<n;i++)cout<<sv<<v[i];cout<<endl;};
template<typename T>void debug(const vector<T>&v){debug(v,v.size());}
template<typename T>void debug(const vector<vector<T>>&v){for(auto &vv:v)debug(vv,vv.size());}
template<typename T>void debug(stack<T> st){while(!st.empty()){cout<<st.top()<<" ";st.pop();}cout<<endl;}
template<typename T>void debug(queue<T> st){while(!st.empty()){cout<<st.front()<<" ";st.pop();}cout<<endl;}
template<typename T>void debug(deque<T> st){while(!st.empty()){cout<<st.front()<<" ";st.pop_front();}cout<<endl;}
template<typename T>void debug(PQ<T> st){while(!st.empty()){cout<<st.top()<<" ";st.pop();}cout<<endl;}
template<typename T>void debug(QP<T> st){while(!st.empty()){cout<<st.top()<<" ";st.pop();}cout<<endl;}
template<typename T>void debug(const set<T>&v){for(auto z:v)cout<<z<<" ";cout<<endl;}
template<typename T>void debug(const multiset<T>&v){for(auto z:v)cout<<z<<" ";cout<<endl;}
template<typename T,typename V>void debug(const map<T,V>&v){for(auto z:v)cout<<"["<<z.first<<"]="<<z.second<<",";cout<<endl;}
template<typename T>vector<vector<T>>vec(ll x, ll y, T w){vector<vector<T>>v(x,vector<T>(y,w));return v;}
ll gcd(ll x,ll y){ll r;while(y!=0&&(r=x%y)!=0){x=y;y=r;}return y==0?x:y;}
vector<ll>dx={1,-1,0,0,1,1,-1,-1};vector<ll>dy={0,0,1,-1,1,-1,1,-1};
template<typename T>vector<T> make_v(size_t a,T b){return vector<T>(a,b);}
template<typename... Ts>auto make_v(size_t a,Ts... ts){return vector<decltype(make_v(ts...))>(a,make_v(ts...));}
template<typename T1, typename T2>ostream &operator<<(ostream &os, const pair<T1, T2>&p){return os << p.first << " " << p.second;}
template<typename T>ostream &operator<<(ostream &os, const vector<T> &v){for(auto &z:v)os << z << " ";cout<<"|"; return os;}
template<typename T>void rearrange(vector<int>&ord, vector<T>&v){
  auto tmp = v;
  for(int i=0;i<tmp.size();i++)v[i] = tmp[ord[i]];
}
template<typename Head, typename... Tail>void rearrange(vector<int>&ord,Head&& head, Tail&&... tail){
  rearrange(ord, head);
  rearrange(ord, tail...);
}
template<typename T> vector<int> ascend(const vector<T>&v){
  vector<int>ord(v.size());iota(ord.begin(),ord.end(),0);
  sort(ord.begin(),ord.end(),[&](int i,int j){return v[i]<v[j];});
  return ord;
}
template<typename T> vector<int> descend(const vector<T>&v){
  vector<int>ord(v.size());iota(ord.begin(),ord.end(),0);
  sort(ord.begin(),ord.end(),[&](int i,int j){return v[i]>v[j];});
  return ord;
}
ll FLOOR(ll n,ll div){return n>=0?n/div:(n-div+1)/div;}
ll CEIL(ll n,ll div){return n>=0?(n+div-1)/div:n/div;}
template<typename T>T min(const vector<T>&v){return *min_element(v.begin(),v.end());}
template<typename T>T max(const vector<T>&v){return *max_element(v.begin(),v.end());}
template<typename T>T acc(const vector<T>&v){return accumulate(v.begin(),v.end(),T(0));};
template<typename T>T reverse(const T &v){return T(v.rbegin(),v.rend());};
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
int popcount(ll x){return __builtin_popcountll(x);};
int poplow(ll x){return __builtin_ctzll(x);};
int pophigh(ll x){return 63 - __builtin_clzll(x);};
template<typename T>T poll(queue<T> &q){auto ret=q.front();q.pop();return ret;};
template<typename T>T poll(priority_queue<T> &q){auto ret=q.top();q.pop();return ret;};
template<typename T>T poll(QP<T> &q){auto ret=q.top();q.pop();return ret;};
template<typename T>T poll(stack<T> &s){auto ret=s.top();s.pop();return ret;};
template< typename T = int >
struct edge {
  int to;
  T cost;
  int id;
  edge():id(-1){};
  edge(int to, T cost = 1, int id = -1):to(to), cost(cost), id(id){}
  operator int() const { return to; }
};

template<typename T>
using Graph = vector<vector<edge<T>>>;
template<typename T>
Graph<T> readGraph(int n,int m,int indexed=1,bool directed=false,bool weighted=false){
  Graph<T> ret(n);
  for(int es = 0; es < m; es++){
    int u,v;
    T w=1;
    cin>>u>>v;u-=indexed,v-=indexed;
    if(weighted)cin>>w;
    ret[u].emplace_back(v,w,es);
    if(!directed)ret[v].emplace_back(u,w,es);
  }
  return ret;
}
template<typename T>
Graph<T> readParent(int n,int indexed=1,bool directed=true){
  Graph<T>ret(n);
  for(int i=1;i<n;i++){
    int p;cin>>p;
    p-=indexed;
    ret[p].emplace_back(i);
    if(!directed)ret[i].emplace_back(p);
  }
  return ret;
}
template<typename T>
struct SCC{
  int n;
  const Graph<T>&G;
  vector<int>index;//各ノードが属する強連結成分の番号
  vector<int>start,visited,low,ord;
  int now_ord,group_num;
  SCC(const Graph<T> &g):G(g),n(g.size()){
    index.assign(n,-1);
    build();
  }
  void build(){
    low.assign(n,0);ord.assign(n,-1);index.assign(n,0);
    visited.reserve(n);
    now_ord=0,group_num=0;
    for(int i=0;i<n;i++){
      if(ord[i]==-1)dfs(i);
    }
    for(auto& x:index)x=group_num-1-x;
  }
  void dfs(int v){
    low[v]=ord[v]=now_ord++;
    visited.push_back(v);
    for(auto to:G[v]){
      if(ord[to]==-1){
        dfs(to);
        low[v]=min(low[v],low[to]);
      }
      else{
        low[v]=min(low[v],ord[to]);
      }
    }
    if(low[v]==ord[v]){
      while(1){
        int u=visited.back();
        visited.pop_back();
        ord[u]=n;
        index[u]=group_num;
        if(u==v)break;
      }
      group_num++;
    }

  }
  Graph<T>scc_graph;
  void build_edges(){
    scc_graph.resize(*max_element(index.begin(),index.end())+1);
    for(int i=0;i<n;i++){
      for(int j=0;j<G[i].size();j++){
        if(index[i]!=index[G[i][j]]){
          scc_graph[index[i]].emplace_back(index[G[i][j]], G[i][j].cost, G[i][j].id);
        }
      }
    }
  }
  vector<int>output(){return index;};
};
struct UnionFind {
  vector<ll> data;
  ll num;
  UnionFind(ll size) : data(size, -1) ,num(size){ }
  bool unite(ll x, ll y) {
    x = root(x); y = root(y);
    if (x != y) {
      if (data[y] < data[x]) swap(x, y);
      data[x] += data[y]; data[y] = x;
	  num--;
    }
    return x != y;
  }
  bool find(ll x, ll y) {
    return root(x) == root(y);
  }
  ll root(ll x) {
    return data[x] < 0 ? x : data[x] = root(data[x]);
  }
  ll size(ll x) {
    return -data[root(x)];
  }
};
int main(){
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res=0,buf=0;
  bool judge = true;
  ll n,m;cin>>n>>m;
  Graph<int>g(n);
  UnionFind uf(n);
  rep(i,0,m){
    ll u,v;cin>>u>>v;u--;v--;
    g[u].EB(v);
    uf.unite(u,v);
  }
  SCC scc(g);
  auto &idx=scc.index;
  ll scsz=max(idx)+1;
  vector<ll>cnt(scsz);
  rep(i,0,n)cnt[idx[i]]++;
  vector<bool>dag(n,true);
  rep(i,0,n){
    if(cnt[idx[i]]>=2)dag[uf.root(i)]=false;
  }
  vector<vector<ll>>v(n);
  rep(i,0,n){
    v[uf.root(i)].PB(i);
  }
  vector<P>ret;
  rep(i,0,n){
    if(v[i].empty())continue;
    if(dag[i]){
      sort(ALL(v[i]),[&](ll x,ll y){return idx[x]<idx[y];});
      rep(j,0,v[i].size()-1)ret.EB(v[i][j]+1,v[i][j+1]+1);
    }
    else{
      rep(j,0,v[i].size()){
        ret.EB(v[i][j]+1,v[i][(j+1)%v[i].size()]+1);
      }
    }
  }
  cout<<ret.size()<<endl;
  for(auto z:ret)cout<<z<<endl;
  return 0;
}
0