Submission #7908987

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Source Code Expand

#include<bits/stdc++.h>
typedef long long ll;
ll gi(){
	ll x=0,f=1;
	char ch=getchar();
	while(!isdigit(ch))f^=ch=='-',ch=getchar();
	while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
	return f?x:-x;
}
bool yes[100010];
int siz[100010];
int main(){
#ifdef XZZSB
	freopen("in.in","r",stdin);
	freopen("out.out","w",stdout);
#endif
	int n=gi(),m=gi(),x,y;
	yes[1]=1;for(int i=1;i<=n;++i)siz[i]=1;
	while(m--){
		x=gi(),y=gi();
		if(!siz[x])continue;
		--siz[x],++siz[y];
		yes[y]|=yes[x];
		if(!siz[x])yes[x]=0;
	}
	int ans=0;for(int i=1;i<=n;++i)ans+=yes[i];
	printf("%d\n",ans);
	return 0;
}

Submission Info

Judge Result