Artifact 71f65eb207acadc5111ef3d876f996bf55ab2ca3
//-------------------------------------------------------------
// Aho-Corasick multi pattern search
// O(|size-of-patterns|) for construction. O(1) per step.
//
// Verified by
// - SRM519 Div1 LV2
//-------------------------------------------------------------
template<int NC=26, char BC='a'>
struct AhoCorasick
{
AhoCorasick( const vector<string>& p ) : link(NC+1) {
// Create a trie
for(int i=0; i<p.size(); ++i) {
AhoCorasick* t = this;
for(int k=0; k<p[i].size(); t=t->link[p[i][k++]-BC])
if(!t->link[p[i][k]-BC])
t->link[p[i][k]-BC]=new AhoCorasick;
t->final.insert(i);
}
// Do BFS and draw failure links, and prepare for substring pattern
queue<AhoCorasick*> Q;
for(int c=0; c<NC; ++c)
if( link[c] ) {
Q.push(link[c]);
link[c]->link[NC] = this; // "c"'s suffix is ""
link[c]->final.insert(final.begin(), final.end());
}
else
link[c] = this;
while( !Q.empty() ) {
AhoCorasick* t=Q.front(); Q.pop();
for(int c=0; c<NC; ++c)
if( t->link[c] ) {
Q.push(t->link[c]);
AhoCorasick* r = t->link[NC]; // "r" is suffix of "t"...
while( !r->link[c] )
r = r->link[NC];
t->link[c]->link[NC] = r->link[c]; // then "rc" is suffix of "tc"
t->link[c]->final.insert(r->link[c]->final.begin(), r->link[c]->final.end());
}
}
}
const AhoCorasick* start() const { return this; }
const AhoCorasick* next(char c) const {
const AhoCorasick* t = this;
while( !t->link[c-BC] )
t = t->link[NC];
return t->link[c-BC];
}
const set<int>& accept() const { return final; }
~AhoCorasick() { for(int i=0; i<NC; ++i) if(link[i]!=this) delete link[i]; }
private:
AhoCorasick() : link(NC+1) {}
vector<AhoCorasick*> link;
set<int> final;
};