const printSteps = false; // set this to true

  firstStep = firstMove()
  S = new Set()   // "safe" cells to explore
  Q = new Set()   // cells that need more information about neighbors
  S.add(firstStep)
  
  while game is not over:
    if S is empty:
      x = selectRandomSquare()
      S.add(x)  
    
    while S is not empty:
      x = S.remove()
      probe(x)    // probe means uncover
      if x is mine:
        return failure
      if AFN(x):   // all-free-neighbor: # neighbor mines - marked cells == 0
        S.add(unmarkedNeighbors(x))
      else:
        Q.add(x)
    
    for q in Q:
      if AMN(q):   // all-mines-neighbor: # neighbor mines - marked cells == # of unmarked cells
        for y in unmarkedNeighbors(q):
          mark(y)   // mark cell y as mine
        Q.remove(q)
     
     for q in Q:
      if AFN(q):
        S.add(unmarkedNeighbors(q))
        Q.remove(q)  
        
   return success