mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-24 21:41:08 +00:00
49 lines
1.5 KiB
Python
49 lines
1.5 KiB
Python
|
# Author: OMKAR PATHAK
|
|||
|
|
|
|||
|
|
import Stack
|
|||
|
|
|
|||
|
|
def isOperand(char):
|
|||
|
|
return (ord(char) >= ord('a') and ord(char) <= ord('z')) or (ord(char) >= ord('A') and ord(char) <= ord('Z'))
|
|||
|
|
|
|||
|
|
def precedence(char):
|
|||
|
|
if char == '+' or char == '-':
|
|||
|
|
return 1
|
|||
|
|
elif char == '*' or char == '/':
|
|||
|
|
return 2
|
|||
|
|
elif char == '^':
|
|||
|
|
return 3
|
|||
|
|
else:
|
|||
|
|
return -1
|
|||
|
|
|
|||
|
|
def infixToPostfix(myExp, myStack):
|
|||
|
|
postFix = []
|
|||
|
|
for i in range(len(myExp)):
|
|||
|
|
if (isOperand(myExp[i])):
|
|||
|
|
postFix.append(myExp[i])
|
|||
|
|
elif(myExp[i] == '('):
|
|||
|
|
myStack.push(myExp[i])
|
|||
|
|
elif(myExp[i] == ')'):
|
|||
|
|
topOperator = myStack.pop()
|
|||
|
|
while(not myStack.isEmpty() and topOperator != '('):
|
|||
|
|
postFix.append(topOperator)
|
|||
|
|
topOperator = myStack.pop()
|
|||
|
|
else:
|
|||
|
|
while (not myStack.isEmpty()) and (precedence(myExp[i]) <= precedence(myStack.peek())):
|
|||
|
|
postFix.append(myStack.pop())
|
|||
|
|
myStack.push(myExp[i])
|
|||
|
|
|
|||
|
|
while(not myStack.isEmpty()):
|
|||
|
|
postFix.append(myStack.pop())
|
|||
|
|
return ' '.join(postFix)
|
|||
|
|
|
|||
|
|
if __name__ == '__main__':
|
|||
|
|
myExp = 'a+b*(c^d-e)^(f+g*h)-i'
|
|||
|
|
myExp = [i for i in myExp]
|
|||
|
|
print('Infix:',' '.join(myExp))
|
|||
|
|
myStack = Stack.Stack(len(myExp))
|
|||
|
|
print('Postfix:',infixToPostfix(myExp, myStack))
|
|||
|
|
|
|||
|
|
# OUTPUT:
|
|||
|
|
# Infix: a + b * ( c ^ d - e ) ^ ( f + g * h ) - i
|
|||
|
|
# Postfix: a b c d ^ e - f g h * + ^ * + i -
|