OJ-Problems-Source/HDOJ/1869_autoAC.cpp
2016-08-17 15:13:51 +08:00

59 lines
1.4 KiB
C++

#include<iostream>
#include<cstdio>
#include<queue>
#include<vector>
#include<cstring>
#include<map>
#define MAX_V 110
#define INF 0x7ffffff
using namespace std;
map <string,int> name;
int ans[MAX_V][MAX_V],d[MAX_V][MAX_V],dd[MAX_V][MAX_V];
bool ok[MAX_V][MAX_V];
int main()
{
int n,m,a,b;
while(~scanf("%d%d",&n,&m))
{
memset(d,0,sizeof(d));
memset(ans,0,sizeof(ans));
memset(ok,0,sizeof(ok));
while(m--)
{
scanf("%d%d",&a,&b);
ans[a][b]=ans[b][a]=d[a][b]=d[b][a]=1;
ok[a][b]=ok[b][a]=1;
}
int times=6;
while(times--){
memset(dd,0,sizeof(dd));
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
for(int k=0;k<n;k++){
dd[i][j]+=ans[i][k]*d[k][j];
}
}
}
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
ans[i][j]=dd[i][j];
}
}
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
if(ans[i][j]!=0) ok[i][j]=1;
}
}
}
int flag=1;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
if(ok[i][j]==0)
flag=0;
}
}
puts(flag?"Yes":"No");
}
return 0;
}