Submission #2242009

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Source Code Expand

#include<iostream>
#include<cstdio>
#include<bitset>
#define MN 100000
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 n,m,a[MN+5],b[MN+5],num=0,ans=0;
bitset<400*399/2+5> fail,s[405];
int main()
{
	n=read();m=read();
	for(int i=1;i<=n;++i) for(int j=i+1;j<=n;++j)
		++num,s[i][num]=1,s[j][num]=1;
	for(int i=1;i<=m;++i) a[i]=read(),b[i]=read();
	for(int i=m;i;--i)
	{
		fail|=s[a[i]]&s[b[i]];
		s[a[i]]|=s[b[i]];s[b[i]]|=s[a[i]];
	}
	for(int i=1;i<=num;++i) if(!fail[i]) ++ans;
	cout<<ans; 
	return 0;
}

Submission Info

Judge Result