MinimalMCTSNode.h

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#pragma once 

#include "MCTSBase.h"

template<typename this_t, typename HYP>
class MinimalMCTSNode : public MCTSBase<this_t,HYP> {   
    using Super = MCTSBase<this_t,HYP>;
    using Super::Super; // get constructors

    using data_t = typename HYP::data_t;
    
    virtual generator<HYP&>  search_one(HYP& current) override {
        if(DEBUG_MCTS) DEBUG("MinimalMCTSNode SEARCH ONE ", this, "\t["+current.string()+"] ", (unsigned long) this->nvisits);
    
        auto c = this->descend_to_childless(current); //sets current and returns the node. 
        
        while(not current.is_evaluable()) {
            c->add_children(current); 
            
            // find the highest prior child
            auto neigh = current.neighbors();
            std::vector<double> children_lps(neigh,-infinity);
            for(int k=0;k<neigh;k++) {
                children_lps[k] = current.neighbor_prior(k);
            }
            
            auto idx = arg_max_int(neigh, [&](const int i) -> double {return children_lps[i];} ).first;
            current.expand_to_neighbor(idx);
            c = &c->children[idx];
        }
        
        c->process_evaluable(current);
        co_yield current;
    }
};