Submission #10378291

---

Source Code Expand

#include <bits/stdc++.h>
#pragma GCC optimize("Ofast", "unroll-loops")
using namespace std;
#define ll long long
#define int ll
#define FOR(i,a,b) for (int i = (a); i<(b); i++)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)
#define RREP(i,n) for (int i=(n)-1; i>=0; i--)
#define f first
#define s second
#define pb push_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)(x.size())
#define SQ(x) (x)*(x)
#define pii pair<int, int>
#define endl '\n'
//#define TOAD
#ifdef TOAD
#define bug(x) cerr<<__LINE__<<": "<<#x<<" is "<<x<<endl
#define IOS() 
#else
#define bug(...)
#define IOS() ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
#endif
const ll inf = 1ll<<60;
const int iinf=2147483647;
const ll mod = 1e9+7;
const int maxn=1e6+5;
signed main (){
  IOS();
  int n, m; cin>>n>>m;
  vector<int> vc(n);
  REP(i,n) vc[i]=1;
  vector<bool> can(n);
  can[0]=1;
  //vc[0]=0;
  REP(i,m){
    int x, y; cin>>x>>y;
    if (can[x-1]) can[y-1]=true;
    vc[x-1]--;
    vc[y-1]++;
    if (vc[x-1]<=0) can[x-1]=false;

  }
  int ans=0;
  REP(i,n){
    if (can[i]) ans++;
  }
  cout<<ans<<endl;
}

Submission Info

Judge Result