Question { Patni, 47493 }

Evaluate the following prefix expression " ++ 26 + - 1324"

Answer

++26 + -1324
METHOD:-
Start scanning the string from the right one character at a time.
If it is an operand, push it in stack.
If it is an operator, pop opnd1, opnd2 and perform the operation, specified by the operator. Push the result in the stack.
Repeat these steps until arr of input prefix strings ends.
Solution
1)Push 4,2,13 in stack one by one
2) - operator encountered
3)Take out 13 and 2 from stack and perform operation
4)Now Stack consist of 4,11
5)+ operator encountered
6)Now Stack consist of 15
7)Now push 6 in stack,Hence Now Stack consist of 15,6,2
8)Perform add operation + encountered
9)Now Stack consist of 15,8
10)+ operator encountered
11)Now Stack consist of 23

Hence Answer is 23