Prefix expression P59813
This problem is marked as deprecated.
Although this problem remains in the system because of historic reasons, it may have some issues and should not be used anymore.
Deprecation indication: Please use P20006 instead.
Write a program that reads a prefix expression, and prints the result of evaluate it. The possible operators are sum, subtraction and multiplication. The operands are natural numbers between 0 and 9 (both included).
Input
Input is a prefix expression. It means that always appears the operator before its operands. For instance, the expression 4 + 3 would be:
+ 4 3
The expression 8 * (4 + 3) would be:
* 8 + 4 3
The expression (2 − 8) * (4 + 3) would be:
* - 2 8 + 4 3
Output
Your program must print an integer: the result of evaluate the expression.
Observation
Use recursion (not tables). Notice that an expression or is a digit, or is an operator followed by an expression followed by another expression.
Input
+ 4 3
Output
7
Input
* 8 + 4 3
Output
56
Input
* - 2 8 + 4 3
Output
-42
- Author
- Salvador Roura
- Language
- English
- Translator
- Carlos Molina
- Original language
- Catalan
- Other languages
- Catalan
- Official solutions
- C++
- User solutions
- C++ Python