結果

問題 No.1553 Lovely City
ユーザー 👑 tute7627
提出日時 2021-06-18 21:50:47
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 277 ms / 2,000 ms
コード長 8,612 bytes
コンパイル時間 3,263 ms
コンパイル使用メモリ 220,516 KB
最終ジャッジ日時 2025-01-22 09:12:05
ジャッジサーバーID
(参考情報)
judge5 / judge5
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 AC * 2
other AC * 26
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ソースコード

diff #
プレゼンテーションモードにする

//#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;//
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;
}
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