zerowing 發(fā)表于 2015-9-15 11:29 6 V6 W0 K7 J/ K應(yīng)該只有24個(gè)。5 |" A; X. P0 [- O& J C (7,3)-C(2,2)*C(5,1)-C(4,3)-2=24, }" w. Q) I( Z' l: I% [ 解釋:7條線中任意去三條的組合數(shù) - 取兩條不 ...