#define PROBLEM "https://judge.yosupo.jp/problem/maximum_independent_set" #include "../maximum_independent_set.hpp" #include "../../util/template.hpp" int main(){ lint n,m; cin>>n>>m; auto g=load_graph0(n,m); auto e=maximum_independent_set(g); cout<<e.size()<<endl; output(e); }
#line 1 "graph_tree/test/LC_maximum_independent_set.test.cpp" #define PROBLEM "https://judge.yosupo.jp/problem/maximum_independent_set" #line 2 "graph_tree/maximum_independent_set.hpp" #include<tuple> #include<vector> #include<bitset> #line 4 "graph_tree/graph_template.hpp" #include<iostream> /** * @brief グラフテンプレート */ using graph=std::vector<std::vector<int>>; template<typename T> using graph_w=std::vector<std::vector<std::pair<int,T>>>; graph load_graph(int n,int m){graph g(n);for(int i=0;i<m;++i){int s,t;std::cin>>s>>t;--s;--t;g[s].push_back(t);g[t].push_back(s);}return g;} graph load_digraph(int n,int m){graph g(n);for(int i=0;i<m;++i){int s,t;std::cin>>s>>t;--s;--t;g[s].push_back(t);}return g;} graph load_graph0(int n,int m){graph g(n);for(int i=0;i<m;++i){int s,t;std::cin>>s>>t;g[s].push_back(t);g[t].push_back(s);}return g;} graph load_digraph0(int n,int m){graph g(n);for(int i=0;i<m;++i){int s,t;std::cin>>s>>t;g[s].push_back(t);}return g;} graph load_tree(int n){graph g(n);for(int i=0;i<n-1;++i){int s,t;std::cin>>s>>t;--s;--t;g[s].push_back(t);g[t].push_back(s);}return g;} graph load_tree0(int n){graph g(n);for(int i=0;i<n-1;++i){int s,t;std::cin>>s>>t;g[s].push_back(t);g[t].push_back(s);}return g;} graph load_treep(int n){graph g(n);for(int i=0;i<n-1;++i){int t;std::cin>>t;g[i+1].push_back(t);g[t].push_back(i+1);}return g;} template<typename T>graph_w<T> load_graph_weight(int n,int m){graph_w<T> g(n);for(int i=0;i<m;++i){int s,t;T u;std::cin>>s>>t>>u;--s;--t;g[s].emplace_back(t,u);g[t].emplace_back(s,u);}return g;} template<typename T>graph_w<T> load_digraph_weight(int n,int m){graph_w<T> g(n);for(int i=0;i<m;++i){int s,t;T u;std::cin>>s>>t>>u;--s;--t;g[s].emplace_back(t,u);}return g;} template<typename T>graph_w<T> load_graph0_weight(int n,int m){graph_w<T> g(n);for(int i=0;i<m;++i){int s,t;T u;std::cin>>s>>t>>u;g[s].emplace_back(t,u);g[t].emplace_back(s,u);}return g;} template<typename T>graph_w<T> load_digraph0_weight(int n,int m){graph_w<T> g(n);for(int i=0;i<m;++i){int s,t;T u;std::cin>>s>>t>>u;g[s].emplace_back(t,u);}return g;} template<typename T>graph_w<T> load_tree_weight(int n){graph_w<T> g(n);for(int i=0;i<n-1;++i){int s,t;T u;std::cin>>s>>t>>u;--s;--t;g[s].emplace_back(t,u);g[t].emplace_back(s,u);}return g;} template<typename T>graph_w<T> load_tree0_weight(int n){graph_w<T> g(n);for(int i=0;i<n-1;++i){int s,t;T u;std::cin>>s>>t>>u;g[s].emplace_back(t,u);g[t].emplace_back(s,u);}return g;} template<typename T>graph_w<T> load_treep_weight(int n){graph_w<T> g(n);for(int i=0;i<n-1;++i){int t;T u;std::cin>>t>>u;g[i+1].emplace_back(t,u);g[t].emplace_back(i+1,u);}return g;} #line 6 "graph_tree/maximum_independent_set.hpp" /** * @brief 最大独立集合(V<=50) */ std::pair<int,std::bitset<50>> __maximum_independent_set(std::vector<std::bitset<50>>v,std::bitset<50>b=std::bitset<50>()){ int n=v.size(); auto del=[&](int k){ for(int i=0;i<n;++i){ v[k][i]=0; v[i][k]=0; } b[k]=1; }; int t=-1; for(int i=0;i<n;++i)if(b[i]==0)t=i; if(t==-1)return std::make_pair(0,std::bitset<50>()); if(v[t].count()<=1){ for(int i=0;i<n;++i)if(v[t][i])del(i); del(t); auto p=__maximum_independent_set(v,b); p.first++; p.second[t]=1; return p; }else{ std::vector<int>tmp; for(int i=0;i<n;++i)if(v[t][i])tmp.push_back(i); del(t); auto p=__maximum_independent_set(v,b); for(auto e:tmp)del(e); auto q=__maximum_independent_set(v,b); q.first++; q.second[t]=1; return p.first>q.first?p:q; } } std::vector<int> maximum_independent_set(const graph& g){ std::vector<std::bitset<50>>v(g.size()); for(size_t i=0;i<g.size();++i){ for(auto e:g[i]){ v[i][e]=1; } } auto res=__maximum_independent_set(v); std::vector<int>ret; for(size_t i=0;i<res.second.size();++i){ if(res.second[i])ret.push_back(i); } return ret; } #line 2 "util/template.hpp" #pragma GCC optimize("Ofast") #pragma GCC optimize("unroll-loops") #pragma GCC target("avx2") #include<bits/stdc++.h> using namespace std; struct __INIT__{__INIT__(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}}__INIT__; typedef long long lint; #define INF (1LL<<60) #define IINF (1<<30) #define EPS (1e-10) #define endl ('\n') typedef vector<lint> vec; typedef vector<vector<lint>> mat; typedef vector<vector<vector<lint>>> mat3; typedef vector<string> svec; typedef vector<vector<string>> smat; template<typename T>using V=vector<T>; template<typename T>using VV=V<V<T>>; template<typename T>inline void output(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i;f=1;}cout<<endl;} template<typename T>inline void output2(T t){for(auto i:t)output(i);} template<typename T>inline void debug(T t){bool f=0;for(auto i:t){cerr<<(f?" ":"")<<i;f=1;}cerr<<endl;} template<typename T>inline void debug2(T t){for(auto i:t)output(i);} #define loop(n) for(long long _=0;_<(long long)(n);++_) #define _overload4(_1,_2,_3,_4,name,...) name #define __rep(i,a) repi(i,0,a,1) #define _rep(i,a,b) repi(i,a,b,1) #define repi(i,a,b,c) for(long long i=(long long)(a);i<(long long)(b);i+=c) #define rep(...) _overload4(__VA_ARGS__,repi,_rep,__rep)(__VA_ARGS__) #define _overload3_rev(_1,_2,_3,name,...) name #define _rep_rev(i,a) repi_rev(i,0,a) #define repi_rev(i,a,b) for(long long i=(long long)(b)-1;i>=(long long)(a);--i) #define rrep(...) _overload3_rev(__VA_ARGS__,repi_rev,_rep_rev)(__VA_ARGS__) // #define rep(i,...) for(auto i:range(__VA_ARGS__)) // #define rrep(i,...) for(auto i:reversed(range(__VA_ARGS__))) // #define repi(i,a,b) for(lint i=lint(a);i<(lint)(b);++i) // #define rrepi(i,a,b) for(lint i=lint(b)-1;i>=lint(a);--i) // #define irep(i) for(lint i=0;;++i) // inline vector<long long> range(long long n){if(n<=0)return vector<long long>();vector<long long>v(n);iota(v.begin(),v.end(),0LL);return v;} // inline vector<long long> range(long long a,long long b){if(b<=a)return vector<long long>();vector<long long>v(b-a);iota(v.begin(),v.end(),a);return v;} // inline vector<long long> range(long long a,long long b,long long c){if((b-a+c-1)/c<=0)return vector<long long>();vector<long long>v((b-a+c-1)/c);for(int i=0;i<(int)v.size();++i)v[i]=i?v[i-1]+c:a;return v;} // template<typename T>inline T reversed(T v){reverse(v.begin(),v.end());return v;} #define all(n) begin(n),end(n) template<typename T,typename E>bool chmin(T& s,const E& t){bool res=s>t;s=min<T>(s,t);return res;} template<typename T,typename E>bool chmax(T& s,const E& t){bool res=s<t;s=max<T>(s,t);return res;} const vector<lint> dx={1,0,-1,0,1,1,-1,-1}; const vector<lint> dy={0,1,0,-1,1,-1,1,-1}; #define SUM(v) accumulate(all(v),0LL) template<typename T,typename ...Args>auto make_vector(T x,int arg,Args ...args){if constexpr(sizeof...(args)==0)return vector<T>(arg,x);else return vector(arg,make_vector<T>(x,args...));} #define extrep(v,...) for(auto v:__MAKE_MAT__({__VA_ARGS__})) #define bit(n,a) ((n>>a)&1) vector<vector<long long>> __MAKE_MAT__(vector<long long> v){if(v.empty())return vector<vector<long long>>(1,vector<long long>());long long n=v.back();v.pop_back();vector<vector<long long>> ret;vector<vector<long long>> tmp=__MAKE_MAT__(v);for(auto e:tmp)for(long long i=0;i<n;++i){ret.push_back(e);ret.back().push_back(i);}return ret;} using graph=vector<vector<int>>; template<typename T>using graph_w=vector<vector<pair<int,T>>>; template<typename T,typename E>ostream& operator<<(ostream& out,pair<T,E>v){out<<"("<<v.first<<","<<v.second<<")";return out;} constexpr inline long long powll(long long a,long long b){long long res=1;while(b--)res*=a;return res;} #line 4 "graph_tree/test/LC_maximum_independent_set.test.cpp" int main(){ lint n,m; cin>>n>>m; auto g=load_graph0(n,m); auto e=maximum_independent_set(g); cout<<e.size()<<endl; output(e); }