【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 + 10;
const int MAXM = 1e4 + 10;

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

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

void init(){
    memset(color,-1,sizeof(color));
    for(int i = 1; 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 = 0; i < g[now].size(); ++i){
                if(color[g[now][i]] == -1){
                    color[g[now][i]] = 1; b.push(g[now][i]);
                }else if(color[g[now][i]] == 0){
                    return false;
                }
            }
        }
        while(!b.empty()){
            int now = b.front(); b.pop();
            for(int i = 0; i < g[now].size(); ++i){
                if(color[g[now][i]] == -1){
                    color[g[now][i]] = 0; a.push(g[now][i]);
                }else if(color[g[now][i]] == 1){
                    return false;
                }
            }
        }
    }
    return true;
}

int main(){
    while(scanf("%d%d%d%d",&n,&m,&x,&y)!=EOF){
        init();
        for(int i = 1; i <= m; ++i){
            int u,v; scanf("%d%d",&u,&v);
            g[u].push_back(v); g[v].push_back(u);
        }
        for(int i = 1; i <= x; ++i){
            int num; scanf("%d",&num); a.push(num); color[num] = 0;
        }
        for(int i = 1; i <= y; ++i){
            int num; scanf("%d",&num); b.push(num); color[num] = 1;
        }
        if(!solve()){
            printf("NO
"); continue;
        }
        bool flag = true;
        for(int i = 1; i <= n; ++i){
            if(color[i] == -1 && g[i].size() != 0){
                a.push(i);
                if(!solve()){
                    flag = false; break;
                }
            }else if(color[i] == -1 && g[i].size() == 0){
                flag = false; break;
            }
        }
        if(!flag){
            printf("NO
"); continue;
        }else{
            printf("YES
"); continue;
        }
    }
    return 0;
}