Files
OI-source/7.2912.cpp
2023-08-03 09:22:52 +08:00

80 lines
1.5 KiB
C++

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=505;
const int maxm=2005;
int n,m,x[maxm],d[maxm],y[maxm],fa[maxn*3];
inline int ff(int u)
{
int a=u,b;
while(u!=fa[u]) u=fa[u];
while(a!=u)
{
b=fa[a];
fa[a]=u;
a=b;
}
return u;
}
inline void merge(int x,int y)
{
x=ff(x); y=ff(y);
fa[x]=y;
}
int check(int id)
{
for(int i=1;i<=n*3;i++) fa[i]=i;
for(int i=1;i<=m;i++)
{
if(x[i]==id||y[i]==id) continue;
int Xself=x[i]*3,Xeat=x[i]*3-1,Xenemy=x[i]*3-2;
int Yself=y[i]*3,Yeat=y[i]*3-1,Yenemy=y[i]*3-2;
if(d[i]==0)
{
if(ff(Xeat)==ff(Yself)) return i;
if(ff(Xself)==ff(Yeat)) return i;
merge(Xeat,Yeat);
merge(Xself,Yself);
merge(Xenemy,Yenemy);
}
else
{
if(ff(Xself)==ff(Yself)) return i;
if(ff(Xself)==ff(Yeat)) return i;
merge(Xeat,Yself);
merge(Xself,Yenemy);
merge(Xenemy,Yeat);
}
}
return 0;
}
int main()
{
#ifdef local
freopen("pro.in","r",stdin);
#endif
while(scanf("%d%d",&n,&m)==2)
{
for(int i=1;i<=m;i++)
{
char op; scanf("%d%c%d",&x[i],&op,&y[i]);
x[i]++; y[i]++;
d[i]=(op=='>'?1:(op=='='?0:-1));
if(d[i]==-1) d[i]=1,swap(x[i],y[i]);
}
// for(int i=1;i<=m;i++) printf("%d %d %d\n",x[i],d[i],y[i]);
// puts("");
int rd=0,tot=0,id=0;
for(int i=1;i<=n;i++)
{
int v=check(i);
rd=max(rd,v);
if(v==0) tot++,id=i;
}
if(tot==0) puts("Impossible");
else if(tot>1) puts("Can not determine");
else printf("Player %d can be determined to be the judge after %d lines\n",id-1,rd);
}
return 0;
}