GATE CSE 1998 | Question: 19b

Question

Compute the post fix equivalent of the following expression $3^*\log(x+1)-\frac{a}{2}$

Comments

so unary opern of  log(x1+) == x1+log ??

---

yes u can say

---

just construct expression tree and do post order traversal.....no need to worry about priorities

Answer 1

Using Stack (Standard method)

Answer 2

Answer attached

Comments

great..

Answer 3

Why to go for long description, draw tree and enjoy what you want prefix, infix postfix or even converse pre, in and post.

 

Once go from my ans.

Comments

Amazing from where you got this method. It’s outstanding… any reference then share please!

Answer 4

we know that in infix expression, operator that is being evaluated at last is root.

Therefore,  3∗log(x+1)−a/2 infix expression can be shown in tree as-

- is evaluated at last here, so we can write it at first in tree, hence the root.

Similarly for other operators like

(x+1) is evaluated at very first therefore we can write it at last in the below tree.

                  

Now traverse it in postfix fashion like Left Right Root, we can get the following postfix expression as:

 

3x1+log∗a2/−