params = {'depth':[3,1,2,6,4,5,7,8,9,10], 'iterations':[250,100,500,1000], 'learning_rate':[0.03,0.001,0.01,0.1,0.2,0.3], 'l2_leaf_reg':[3,1,5,10,100], 'border_count':[32,5,10,20,50,100,200], 'ctr_border_count':[50,5,10,20,100,200], 'thread_count':4}