逆波兰式(后缀表达式)
a*b/(c+2*d)+e*f+g
->[a*b/(c+2*d)+e*f]g+
->[a*b/(c+2*d)][e*f]+g+
->[ab*]/(c+2*d)][ef*]+g+
->[[ab*]/[c[2*d]+]]ef*+g+
->[ab*][c[2*d]+]/ef*+g+
->ab*c2d*+/ef*+g+
四元式:(其中,t1,t2为中间变量)
(*,a,b,t1)
(*,2,d,t2)
(+,c,t2,t2)
(/,t1,t2,t1)
(*,e,f,t2)
(+,t2,t1,t1)
(+,t1,g,x)