Sam's Lazyy Docs

How the engine actually works

A classical game-search engine — no neural nets, no GPU. It looks at patterns, searches a tree, and iterates. This page walks through each step with live diagrams and the real numbers we measured on the 2-core VPS.

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1 · The loop, line by line

One move in, one move out.

engine/search.cpp · Searcher::search 

        

          

          

            
            
            
          

        

      

    


    
2 · Scoring a move

    
Gomoku is a pattern game.

    

      

        

        

          

            
            
          

          

          

        

      

      

      

    


    
3 · How it iterates

    
Iterative deepening.

    

      

      
      

        Node budget (log scale)
      

      

        
Returned depth
7

        
Best move
6,6

        
Score
781

        
Nodes
793,188

      

    

    


    
4 · Alpha-beta & the transposition table

    
Each candidate is a branch.

    

      

        

        

          

          

            
Root value
5

            
Leaves visited
6 / 6

          

          

          
Transposition table.

        

      

    


    
5 · Forced wins: VCF / VCT

    
Threat search.

    

      

      

        

        

          

          

          

        

      

    


    
6 · Lazy SMP

    
Shared table, shared stop flag.

    

      
        
          
          
          
          
        
        
          worker 0worker 1
          shared TT (128 MB)Zobrist → move/depth/score
          stop flagatomic<bool>
        
        
          
          
          
          
        
      
    

    
Staggering avoids all workers searching the identical tree.


    
7 · Pitfalls

    
Real bugs from building this.

    


    
8 · Real results

    
All numbers measured on the deployment box.

    

      

        WhatBeforeAfterNote
      

      
    

    
The two big wins were algorithmic.