【文件属性】：
文件名称：浙江大学ACM模板库
文件大小：78KB
文件格式：RAR
更新时间：2021-06-26 09:39:57
C/C++ 数据结构 算法 模板
/**
* WishingBone's ACM/ICPC Routine Library
*
* maximum clique solver
*/
#include
using std::vector;
// clique solver calculates both size and consitution of maximum clique
// uses bit operation to accelerate searching
// graph size limit is 63, the graph should be undirected
// can optimize to calculate on each component, and sort on vertex degrees
// can be used to solve maximum independent set
class clique {
public:
static const long long ONE = 1;
static const long long MASK = (1 << 21) - 1;
char* bits;
int n, size, cmax[63];
long long mask[63], cons;
// initiate lookup table
clique() {
bits = new char[1 << 21];
bits[0] = 0;
for (int i = 1; i < 1 << 21; ++i) bits[i] = bits[i >> 1] + (i & 1);
}
~clique() {
delete bits;
}
// search routine
bool search(int step, int size, long long more, long long con);
// solve maximum clique and return size
int sizeClique(vector >& mat);
// solve maximum clique and return constitution
vector consClique(vector >& mat);
};
// search routine
// step is node id, size is current solution, more is available mask, cons is
constitution mask
bool clique::search(int step, int size, long long more, long long cons) {
if (step >= n) {
// a new solution reached
this->size = size;
this->cons = cons;
return true;
}
long long now = ONE << step;
if ((now & more) > 0) {
long long next = more & mask[step];
if (size + bits[next & MASK] + bits[(next >> 21) & MASK] + bits[next >>
42] >= this->size
&& size + cmax[step] > this->size) {
// the current node is in the clique
if (search(step + 1, size + 1, next, cons | now)) return true;
}
}
long long next = more & ~now;
if (size + bits[next & MASK] + bits[(next >> 21) & MASK] + bits[next >> 42]
> this->size) {
// the current node is not in the clique
if (search(step + 1, size, next, cons)) return true;
}
return false;
}
// solve maximum clique and return size
int clique::sizeClique(vector >& mat) {
n = mat.size();
// generate mask vectors
for (int i = 0; i < n; ++i) {
mask[i] = 0;
for (int j = 0; j < n; ++j) if (mat[i][j] > 0) mask[i] |= ONE << j;
}
size = 0;
for (int i = n - 1; i >= 0; --i) {
search(i + 1, 1, mask[i], ONE << i);
cmax[i] = size;
}
return size;
}
// solve maximum clique and return constitution
// calls sizeClique and restore cons
vector clique::consClique(vector >& mat) {
sizeClique(mat);
vector ret;
for (int i = 0; i < n; ++i) if ((cons & (ONE << i)) > 0) ret.push_back(i);
return ret;
}
