二分图匹配

  1 #define IOS ios_base::sync_with_stdio(0); cin.tie(0);
  2 #include <cstdio>//sprintf islower isupper
  3 #include <cstdlib>//malloc  exit strcat itoa system("cls")
  4 #include <iostream>//pair
  5 #include <fstream>//freopen("C:\\Users\\13606\\Desktop\\草稿.txt","r",stdin);
  6 #include <bitset>
  7 //#include <map>
  8 //#include<unordered_map>
  9 #include <vector>
 10 #include <stack>
 11 #include <set>
 12 #include <string.h>//strstr substr
 13 #include <string>
 14 #include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
 15 #include <cmath>
 16 #include <deque>
 17 #include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less
 18 #include <vector>//emplace_back
 19 //#include <math.h>
 20 #include <cassert>
 21 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
 22 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
 23 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
 24 //******************
 25 int abss(int a);
 26 int lowbit(int n);
 27 int Del_bit_1(int n);
 28 int maxx(int a,int b);
 29 int minn(int a,int b);
 30 double fabss(double a);
 31 void swapp(int &a,int &b);
 32 clock_t __STRAT,__END;
 33 double __TOTALTIME;
 34 void _MS(){__STRAT=clock();}
 35 void _ME(){__END=clock();__TOTALTIME=(double)(__END-__STRAT)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}
 36 //***********************
 37 #define rint register int
 38 #define fo(a,b,c) for(rint a=b;a<=c;++a)
 39 #define fr(a,b,c) for(rint a=b;a>=c;--a)
 40 #define mem(a,b) memset(a,b,sizeof(a))
 41 #define pr printf
 42 #define sc scanf
 43 #define ls rt<<1
 44 #define rs rt<<1|1
 45 typedef vector<int> VI;
 46 typedef long long ll;
 47 const double E=2.718281828;
 48 const double PI=acos(-1.0);
 49 //const ll INF=(1LL<<60);
 50 const int inf=(1<<30);
 51 const double ESP=1e-9;
 52 const int mod=(int)1e9+7;
 53 const int N=(int)1e4+10;
 54 
 55 queue<int>good,bad;
 56 struct node
 57 {
 58     int u,v;
 59 }edge[N];
 60 vector<int>v[N];
 61 vector<int>mp[N];
 62 int mark[N],color[N];
 63 bool FLAG;
 64 
 65 bool bfs(int s)
 66 {
 67     color[s] = 1; //连通分支的起点可以染1也可以染0
 68     queue<int>q;
 69     q.push(s);
 70     while (!q.empty())
 71     {
 72         s = q.front();
 73         q.pop();
 74         for (int i = 0; i < (int)mp[s].size(); i ++) {
 75             int t = mp[s][i];
 76             if (color[t] == 0) color[t] =3-color[s], q.push(t); //如果相邻顶点未被染色，则加入
 77             //队列。
 78             if (color[t] == color[s]) { //如果相邻顶点染相同颜色，则不是二分图。
 79                 return false;
 80             }
 81         }
 82     }
 83     return true;
 84 }
 85 
 86 int main()
 87 {
 88     int n,m,x,y;
 89     while(~sc("%d%d%d%d",&n,&m,&x,&y))
 90     {
 91         FLAG=1;
 92         while(!good.empty())good.pop();
 93         while(!bad.empty())bad.pop();
 94         for(int i=1;i<=n;++i)v[i].clear(),mp[i].clear(),mark[i]=color[i]=0;
 95         for(int i=1;i<=m;++i)
 96         {
 97             int U,V;
 98             sc("%d%d",&U,&V);
 99             edge[i]={U,V};
100             v[U].push_back(V);
101             v[V].push_back(U);
102             mp[U].push_back(V);
103             mp[V].push_back(U);
104         }
105         for(int i=1;i<=x;++i)
106         {
107             int tt;
108             sc("%d",&tt);
109             mark[tt]=1;
110             good.push(tt);
111         }
112         for(int i=1;i<=y;++i)
113         {
114             int tt;
115             sc("%d",&tt);
116             mark[tt]=2;
117             bad.push(tt);
118         }
119         bool f=0;
120         while(!good.empty()||!bad.empty())
121         {
122             while(!good.empty())
123             {
124                 int now=good.front();good.pop();
125                 int sz=v[now].size();
126                 for(int i=sz-1;i>=0;--i)
127                 {
128                     int to=v[now][i];v[now].pop_back();
129                     if(mark[to]==0)
130                         bad.push(to);
131                     else if(mark[to]==1)
132                         f=1;
133                     else if(mark[to]==2)
134                         continue;
135                 }
136             }
137             while(!bad.empty())
138             {
139                 int now=bad.front();bad.pop();
140                 int sz=v[now].size();
141                 for(int i=sz-1;i>=0;--i)
142                 {
143                     int to=v[now][i];v[now].pop_back();
144                     if(mark[to]==0)
145                         good.push(to);
146                     else if(mark[to]==1)
147                         continue;
148                     else if(mark[to]==2)
149                         f=1;
150                 }
151             }
152         }
153         if(f)
154         {
155             pr("NO\n");
156         }
157         else
158         {
159             for(int i=1;i<=n;++i)
160             {
161                 if(mark[i]==0&&color[i]==0&&mp[i].size()&&!bfs(i))
162                 {
163                     FLAG=0;
164                     break;
165                 }
166             }
167             for(int i=1;i<=n;++i)
168                 if(mark[i]==0&&color[i]==0)
169                     FLAG=0;
170             if(FLAG)
171                 pr("YES\n");
172             else
173                 pr("NO\n");
174         }
175     }
176     return 0;
177 }
178 
179 /**************************************************************************************/
180 
181 int maxx(int a,int b)
182 {
183     return a>b?a:b;
184 }
185 
186 void swapp(int &a,int &b)
187 {
188     a^=b^=a^=b;
189 }
190 
191 int lowbit(int n)
192 {
193     return n&(-n);
194 }
195 
196 int Del_bit_1(int n)
197 {
198     return n&(n-1);
199 }
200 
201 int abss(int a)
202 {
203     return a>0?a:-a;
204 }
205 
206 double fabss(double a)
207 {
208     return a>0?a:-a;
209 }
210 
211 int minn(int a,int b)
212 {
213     return a<b?a:b;
214 }