mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-18 09:10:16 +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 -
|