158. Evaluate a Postfix Expression
Core1000 ms256 MBSolved by 0%
In postfix notation the operator comes AFTER its two operands, so 2 3 +
means 2 + 3, and no brackets are ever needed.
Read n tokens on one line, integers and the operators + - * /, and print the value
of the expression.
Division truncates toward zero, and never divides by zero. The expression is always valid.
Constraints - `1 ≤ n ≤ 100000` - Operands fit in a 64-bit integer. - The result fits in a 64-bit integer.
Input
The first line contains an integer n, the number of tokens.
The second line contains n space-separated tokens, integers and the operators + - * /, in postfix order.
Output
Print one integer, the value of the expression.
Input3
2 3 +
Output5
Noteis the simplest possible expression
Input5
2 3 + 4 *
Output20
Noteapplies an operator to a previous result
Hints
Four rungs, in order. The last two open once you have submitted an attempt. A wrong one counts.
Hint 1Where to start
Hint 2The approachOpen hint 1 first. This one carries on from it.
Hint 3PseudocodeOpen hint 2 first. This one carries on from it.
Hint 4Full solutionOpen hint 3 first. This one carries on from it.