最大团问题 DP + DFS

| 最大团问题 DP + DFS
| INIT: g[][] 邻接矩阵 ;
| CALL: res = clique(n);
\*==================================================*/
int g[V][V], dp[V], stk[V][V], mx;
int dfs( int n, int ns, int dep){
if (0 == ns) {
if (dep > mx) mx = dep;
return 1;
}
int i, j, k, p, cnt;
for (i = 0; i < ns; i++) {
k = stk[dep][i]; cnt = 0;
if (dep + n - k <= mx) return 0;
if (dep + dp[k] <= mx) return 0;
for (j = i + 1; j < ns; j++) {
p = stk[dep][j];
if (g[k][p]) stk[dep + 1][cnt++] = p;
}
dfs(n, cnt, dep + 1);
}
return 1;
}
int clique( int n){
int i, j, ns;
for (mx = 0, i = n - 1; i >= 0; i--) {
// vertex: 0 ~ n-1
for (ns = 0, j = i + 1; j < n; j++)
if (g[i][j]) stk[1][ ns++ ] = j;
dfs(n, ns, 1); dp[i] = mx;
}
return mx;
}