【HDOJ5971】Wrestling Match（二分图，并查集）

题意：有n个人，m场比赛，x个人为good player，y个人为bad player，

每场比赛两个人分分别为good和bad，问good和bad是否会冲突

1 ≤ N≤ 1000，1 ≤M ≤ 10000

思路：二分图

根据已有的点暴力遍历，判有没有冲突即可

并查集也能写，队友写的搜索

 #include <stdio.h>
 #include <vector>
 #include <algorithm>
 #include <string.h>
 #include <limits.h>
 #include <string>
 #include <iostream>
 #include <queue>
 #include <math.h>
 #include <map>
 using namespace std;
 typedef long long int lint;

 const int MAXN = 1e3 + ;
 const int MAXM = 1e4 + ;

 vector<int> g[MAXN];
 queue<int> a,b;

 int n,m,x,y;
 int color[MAXN];

 void init(){
     memset(color,-,sizeof(color));
     for(int i = ; i <= n; ++i){ g[i].clear();}
     while(!a.empty()){ a.pop();}
     while(!b.empty()){ b.pop();}
 }

 bool solve(){
     while(!a.empty() || !b.empty()){
         while(!a.empty()){
             int now = a.front(); a.pop();
             for(int i = ; i < g[now].size(); ++i){
                 if(color[g[now][i]] == -){
                     color[g[now][i]] = ; b.push(g[now][i]);
                 }else if(color[g[now][i]] == ){
                     return false;
                 }
             }
         }
         while(!b.empty()){
             int now = b.front(); b.pop();
             for(int i = ; i < g[now].size(); ++i){
                 if(color[g[now][i]] == -){
                     color[g[now][i]] = ; a.push(g[now][i]);
                 }else if(color[g[now][i]] == ){
                     return false;
                 }
             }
         }
     }
     return true;
 }

 int main(){
     while(scanf("%d%d%d%d",&n,&m,&x,&y)!=EOF){
         init();
         for(int i = ; i <= m; ++i){
             int u,v; scanf("%d%d",&u,&v);
             g[u].push_back(v); g[v].push_back(u);
         }
         for(int i = ; i <= x; ++i){
             int num; scanf("%d",&num); a.push(num); color[num] = ;
         }
         for(int i = ; i <= y; ++i){
             int num; scanf("%d",&num); b.push(num); color[num] = ;
         }
         if(!solve()){
             printf("NO\n"); continue;
         }
         bool flag = true;
         for(int i = ; i <= n; ++i){
             if(color[i] == - && g[i].size() != ){
                 a.push(i);
                 if(!solve()){
                     flag = false; break;
                 }
             }else if(color[i] == - && g[i].size() == ){
                 flag = false; break;
             }
         }
         if(!flag){
             printf("NO\n"); continue;
         }else{
             printf("YES\n"); continue;
         }
     }
     return ;
 }