OJ-Problems-Source/HDOJ/5222_autoAC.cpp

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#include<cstdio>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
#pragma comment(linker, "/STACK:102400000,102400000")
const int maxn = 1000005;
int N,M1,M2,cnt;
int fa[maxn],vis[maxn];
vector<int>G[maxn];
int find_father(int u){
return u == fa[u] ? u : fa[u] = find_father(fa[u]);
}
void init(){
for(int i = 1; i <= N; i++) fa[i] = i;
for(int i = 1; i <= N; i++) G[i].clear();
}
bool dfs(int v){
vis[v] = -1;
for(int i = 0; i < G[v].size(); i++){
int e = G[v][i];
if(vis[e] < 0) return false;
if(!vis[e] && !dfs(e)) return false;
}
vis[v] = 1;
return true;
}
int solve(){
memset(vis,0,sizeof(vis));
for(int i = 1; i <= N; i++){
int e = find_father(i);
if(!vis[e]){
if(!dfs(e)) return true;
}
}
return false;
}
int main(){
int T;
scanf("%d",&T);
while(T--){
scanf("%d%d%d",&N,&M1,&M2);
int u,v,ok = 0;
init();
getchar();
for(int i = 0; i < M1; i++){
scanf("%d%d",&u,&v);
int f1 = find_father(u);
int f2 = find_father(v);
if(f1 == f2)
ok = 1;
else
fa[f1] = f2;
}
for(int i = 0; i < M2; i++){
scanf("%d%d",&u,&v);
if(!ok){
int f1 = find_father(u);
int f2 = find_father(v);
G[f1].push_back(f2);
}
}
if(ok)
printf("YES\n");
else{
ok = solve();
if(ok)
printf("YES\n");
else
printf("NO\n");
}
}
return 0;
}