ZOJ 1492 Maximum Clique 搜索最大团

#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<vector>
using namespace std;
const int maxn=100;
bool g[maxn][maxn],found;
int ans,list[maxn][maxn],n,len[maxn],mc[maxn];
void dfs(int size)
{
 int i,j,k;
 if(len[size]==0)
 	{
 	 if(size>ans)
 	 	{
 	 	 ans=size;
 	 	 found=true;
		}
	 return ;
	}
 for( k=0;k<len[size]&&!found;++k)
 	{
 	 if(size+len[size]-k<=ans)break;
 	 int i=list[size][k];
 	 if(size+mc[i]<=ans)break;
 	 for(j=k+1,len[size+1]=0;j<len[size];++j)
 	 	{
 	 	 if(g[i][list[size][j]])
 	 	 	list[size+1][len[size+1]++]=list[size][j];
		}
	 	 dfs(size+1);
	}
 
}

void max_cluster()
{
 int i,j;
 mc[n]=ans=1;
 for(int i=n-1;i>0;--i)
 	{
 	 found=false;len[1]=0;
 	 for(int j=i+1;j<=n;++j)
 	 	if(g[i][j])list[1][len[1]++]=j;
 	 dfs(1);
 	 mc[i]=ans;
	}
}
int main()
{
 freopen("t.txt","r",stdin);
 while(scanf("%d",&n))
 	{
 	 if(!n)return 0;
 	 memset(g,0,sizeof(g));
 	 memset(mc,0,sizeof(mc));
 	 memset(list,0,sizeof(list));
 	 for(int i=1;i<=n;i++)
 	 	for(int j=1;j<=n;j++)
 	 	    {
 	 	     int t;scanf("%d",&t);
 	 	     if(t==1)g[i][j]=1;
			}
 	 max_cluster();
 	 printf("%d\n",ans);
	}
 return 0;
}