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- #include <bits/stdc++.h>
- using namespace std;
- #define ll long long
- #define test int t; cin>>t; for(int cs=1;cs<=t;cs++)
- bool v[100005];
- vector<ll>g[100005];
- map<ll,ll>ss;
- void dfs(ll in)
- {
- if(v[in]) return;
- v[in]=1;
- for(ll i=0;i<g[in].size();i++)
- {
- if(v[g[in][i]]==0)
- {
- dfs(g[in][i]);
- }
- }
- topsort.push_back(in);
- }
- int main()
- {
- ios_base::sync_with_stdio(0);
- cin.tie(0);cout.tie(0);
- test
- {
- ll n,m,i,j,k,l=0;
- cin>>n>>m;
- for(i=0;i<n+5;i++)
- {
- g[i].clear();
- v[i]=0;
- }
- ss.clear();
- for(i=0;i<m;i++)
- {
- ll a,b;
- cin>>a>>b;
- g[a].push_back(b);
- ss[b]++;
- }
- priority_queue<pair<ll,ll>>q;
- for(i=1;i<=n;i++)
- {
- q.push({-ss[i],i});
- }
- while(!q.empty())
- {
- if(v[q.top().second]==0)
- {
- l++;
- dfs(q.top().second);
- }
- q.pop();
- }
- cout<<l<<endl;
- }
- return 0;
- }
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