Submission #2240194

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Source Code Expand

#include<iostream>
#include<cstdio>
#define MN 400
using namespace std;
inline int read()
{
	int x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
	return x*f;
}
int a[100005],b[100005],fail[405],res[MN+5][MN+5],n,m,ans=0;
int main()
{
	n=read();m=read();
	for(int i=1;i<=m;++i) a[i]=read(),b[i]=read();
	for(int i=1;i<=n;++i)
	{
		res[i][i]=1;
		for(int j=m;j;--j)
		{
			if(res[i][a[j]]&&res[i][b[j]]) {fail[i]=1;break;}
			if(res[i][a[j]]) res[i][b[j]]=1;
			if(res[i][b[j]]) res[i][a[j]]=1;
		}
	}
	for(int i=1;i<=n;++i) for(int j=i+1;j<=n;++j) 
		if(!res[i][j]&&!res[j][i]&&!fail[j]&&!fail[i]) ++ans;
	cout<<ans;
	return 0;
}

Submission Info

Judge Result