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Cod sursa(job #542345)
#include<fstream>
#include<vector>
#define DIM 100004
using namespace std;
vector<int>G[DIM];
vector<int>K[DIM];
int N,M,Q,grad[DIM],t[DIM],a,b,rez;
void afla(int a,int b);
void dfs(int k);
int main()
{
ifstream fin("gossips.in");
ofstream fout("gossips.out");
fin>>N>>M>>Q;
int i,q;
for(i=1;i<=M;i++)
{
fin>>a>>b;
G[a].push_back(b);
grad[b]++;
}
for(i=1;i<=N;i++)
if(grad[i]==0)
dfs(i);
for(i=1;i<=Q;i++)
{
fin>>q>>a>>b;
if(q==1)
{
rez=0;
afla(a,b);
if(rez==0)
fout<<"NO"<<"\n";
else
fout<<"YES"<<"\n";
}
else
K[a].push_back(b);
}
return 0;
}
void dfs(int k)
{
for(int i=0;i<G[k].size();i++)
t[G[k][i]]=k,dfs(G[k][i]);
}
void afla(int a,int b)
{
int aux;
while(a!=0 && rez==0)
{
for(int i=0;i<K[a].size();i++)
{
aux=K[a][i];
while(aux!=0 && rez==0)
{
if(aux==b)
rez=1;
aux=t[aux];
}
}
a=t[a];
}
}