Comparing rpn (postfix) expressions for equivalency

How would one compare any two postfix notated expressions for equivalency?

In the simplest example, foo(a, b) returns True for

a = [3, 5, 'MUL']

b = [5, 3, 'MUL']


What would foo() look like in python? I imagine that one way is to evaluate both expressions and normalize them somehow. I expect that this is a well defined process but haven't found it yet.

foo()

Edit 1:

This was a poorly worded question. I will try with better/more examples, and appreciate your patience as I try and ask the question clearly and precisely.

expr1 = [a, b, 'MUL']

expr2 = [b, a, 'MUL']


OR

expr1 = [a, b, 1, 'ADD', 'MUL']

expr2 = [a, b, 'MUL', a, 'ADD']


2 Answers
2

Here I have tried your problem with a solution, it works , if you have more choices you can add :

a = [3, 5, 'MUL']
b = [5, 3, 'MUL']


def postfix_calc(value, z):
return {
'MUL': lambda c: a[0]*a[1],
'ADD': lambda c: a[0]+a[1],
'SUB': lambda c: a[0]-a[1],
'DIV': lambda c: a[0]/a[1]
}.get(value)(z)


def foo(x, y):
val1 = postfix_calc(x[2], x)
val2 = postfix_calc(y[2], y)
if val1 == val2:
return True
else:
return False


print(foo(a,b))


Since you already have the postfix evaluation. you wcould have it like this then.

foo(a,b):
res_a = postfix(a)
res_b = postfix(b)
if res_a = res_b:
return True
return False


I think this is the simplest solution you're looking for?

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