Answer to Question #202025 in Python for laureeeeeee

Question

Can you please rewrite the code below. Please, thank you. This is the question:

Create a program that will convert an infix expression entered by the user to its equivalent prefix and postfix expression Sample Output: Enter an Infix Expression: a+b^(c^d- e/(f+g)+(h^i)^j) <input> Postfix Expression: abcd^efg+/- hi^j^+^+ <compute> Prefix Expression: +a^b+- ^cd/e+fg^^hij <compute>

prefix = input("Enter an Infix Expression: ')

infixstack = []

 x = len(prefix)

for i in range (x) :

index = (x-1)-i

if prefix[index == " + " or prefix[index] == "-" or prefix[index] == "-" or prefix[index] == "*':

op1 = infixstack.pop()

op2 = infixstack.pop()

Infix = "(" op1 + " " + prefix[index] + " " + op2 + ")"

infixstack.append(Infix)

 else:

ifixstack.append(prefix[index])

print(*infixstack)

Answer 1

def inf2post(s):
    var = set('abcdefghijklmnopqrstuvwxyz')
    op = {'+':0, '-':0, '*':1, '/':1, '^':2}


    ops = []
    postfix = []


    for ch in s:
        if ch == ' ':
            continue
        if ch in var:
            postfix.append(ch)
        elif ch == '(':
            ops.append(ch)
        elif ch == ')':
            while ops[-1] != '(':
                postfix.append(ops.pop())
            ops.pop()
        elif ch in op:
            if len(ops) == 0:
                ops.append(ch)
            elif ops[-1] != '(' and op[ops[-1]] >= op[ch]:
                while ops and ops[-1] != '(' and op[ops[-1]] >= op[ch]:
                    postfix.append(ops.pop())
                ops.append(ch)
            else:
                ops.append(ch)
    while len(ops):
        postfix.append(ops.pop())


    return postfix


def inf2pre(s):
    ss = ''
    for i in range(len(s)-1,-1,-1):
        if s[i] == '(':
            ss += ')'
        elif s[i] == ')':
            ss += '('
        else:
            ss += s[i]
    L = inf2post(ss)
    return L[::-1]


infix = input('Enter an Infix Expression: ')


postfix = inf2post(infix)
print('Postfix:', end= ' ')
for ch in postfix:
    print(ch, end='')
print()


prefix = inf2pre(infix)
print('Prefix:', end= ' ')
for ch in prefix:
    print(ch, end='')
print()