Evaluate Reverse Polish Notation (RPN) - Leetcode 150 - Stacks (Python)

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[GregHogg]

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[JoeTan-nqfq]

Using eval() for shorter code
stack = [] # stack contains strings
for c in tokens:
if c in '+-*/':
b, a = stack.pop(), stack.pop()
stack.append(str(int(eval(a + c + b))))
else:
stack.append(c)
return int(stack[0])

[masemark]

Best channel I’ve discovered this year! Great content, thank you

[badrlakhal]

Pay attention, in Python 2, the / operator performs integer division, and rounds towards negative infinity. So 6/-132 gives -1, and of course int(6/-132) also gives -1. In Python 3, the / operator performs float division, so 6/-132 is -0.045. Then the int function truncates decimals, so int(6/-132) is 0.

[mohitsonwane]

I feel that this statement in the question is the most important. "The division between two integers always truncates toward zero."

[ThePersopolis]

Could you not use stk.append( int(a / b) ) for division instead of the if/else and use of ceil and floor?

[saleheen]

Ceil and floor giving error in leetcode although in my local compiler the output is correct.
Try this instead:
int(float(a)/b)

[anirbandas]

For js/ ts ceil doesn't work i think i had to use trunc ..

[VitaliyBorisok]

Noticed that in Java implementation you also used ceil and floor. But it is redundant for integer division. It always drops the part after dot.