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#-----------------------------------------------------------------------

# evaluate.py

#-----------------------------------------------------------------------

import stdio

import math

from arraystack import Stack

#-----------------------------------------------------------------------

# Read a fully parenthesized numeric expression from standard input,

# evaluate it, and write the resulting number to standard output.

ops = Stack()

values = Stack()

while not stdio.isEmpty():

token = stdio.readString()

if token == '+': ops.push(token)

elif token == '-': ops.push(token)

elif token == '*': ops.push(token)

elif token == 'sqrt': ops.push(token)

elif token == ')':

# Pop, evaluate, and push result.

op = ops.pop()

value = values.pop()

if op == '+': value = values.pop() + value

elif op == '-': value = values.pop() - value

elif op == '*': value = values.pop() * value

elif op == 'sqrt': value = math.sqrt(value)

values.push(value)

elif token != '(':

# Token not operator or paren, so push float value.

values.push(float(token))

stdio.writeln(values.pop())

#-----------------------------------------------------------------------

# more expression1.txt

# ( 1 + ( ( 2 + 3 ) * ( 4 * 5 ) ) )

# python evaluate.py < expression1.txt

# 101.0

# more expression2.txt

# ( ( 1 + sqrt ( 5.0 ) ) * 0.5 )

# python evaluate.py < expression2.txt

# 1.618033988749895