http://www.lydsy.com/JudgeOnline/problem.php?id=3632
裸一般图最大团
http://www.cnblogs.com/zhj5chengfeng/archive/2013/07/29/3224092.html
//#define _TEST _TEST #include <cstdio> #include <cstring> #include <cstdlib> #include <iostream> #include <cmath> #include <algorithm> using namespace std; /************************************************ Code By willinglive Blog:http://willinglive.cf ************************************************/ #define rep(i,l,r) for(int i=(l),___t=(r);i<=___t;i++) #define per(i,r,l) for(int i=(r),___t=(l);i>=___t;i--) #define MS(arr,x) memset(arr,x,sizeof(arr)) #define LL long long #define INE(i,u,e) for(int i=head[u];~i;i=e[i].next) inline const int read() {int r=0,k=1;char c=getchar();for(;c<'0'||c>'9';c=getchar())if(c=='-')k=-1; for(;c>='0'&&c<='9';c=getchar())r=r*10+c-'0';return k*r;} ///////////////////////////////////////////////// int n; bool map[51][51]; int s[51][51],f[51]; int ans; ///////////////////////////////////////////////// bool dfs(int cur,int res) { if(!cur) { if(res>ans) { ans=res; return 1; } return 0; } rep(i,1,cur) { int u=s[res][i]; if(res+cur-i+1<=ans) return 0; if(res+f[u]<=ans) return 0; int top=0; rep(j,i+1,cur) if(map[u][s[res][j]]) s[res+1][++top]=s[res][j]; if(dfs(top,res+1)) return 1; } return 0; } int maxclique() { per(i,n,1) { int cur=0; rep(j,i+1,n) if(map[i][j]) s[1][++cur]=j; dfs(cur,1); f[i]=ans; } return ans; } ///////////////////////////////////////////////// void input() { n=read(); int x,y; while(~scanf("%d%d",&x,&y)) map[x][y]=map[y][x]=1; } void solve() { printf("%d\n",maxclique()); } ///////////////////////////////////////////////// int main() { #ifndef _TEST freopen("std.in","r",stdin); freopen("std.out","w",stdout); #endif input(),solve(); return 0; }