Answer to Question #270927 in Algorithms for Ashu

Question

Find the infix equivalents of the following postfix equivalents:

(A) A B + C * D –

Answer 1

convert postfix to infix:

• Scan the given postfix expression from left to right character by character.
• If the character is an operand, push it into the stack.
• But if the character is an operator, pop the top two values from stack.
• Concatenate this operator with these two values (2^nd top value+operator+1^st top value) to get a new string.
• Now push this resulting string back into the stack.
• Repeat this process until the end of postfix expression. Now the value in the stack is the infix expression.

Postfix Expression Stack (Infix)

B + C * D – A

+ C * D – AB

C * D – (A+B)

* D – (A+B)C

   D – ((A+B)*C)

   – ((A+B)*C)D

(((A+B)*C)-D)