题目描述
- 根据 逆波兰表示法,求表达式的值。
- 有效的算符包括 +、-、*、/ 。每个运算对象可以是整数,也可以是另一个逆波兰表达式。
- 整数除法只保留整数部分。
- 给定逆波兰表达式总是有效的。即表达式总会得出有效数值且不存在除数为 0 的情况。
example
input : tokens = {
"2","1","+","3","*"}
output : 9
note : 该算式转化为常见的中缀算术表达式为:((2 + 1) * 3) = 9
input : tokens = {"4","13","5","/","+"}
output : 6
note : 该算式转化为常见的中缀算术表达式为:(4 + (13 / 5)) = 6
input : tokens = {
"10","6","9","3","+","-11","*","/","*","17","+","5","+"}
output : 22
note : 该算式转化为常见的中缀算术表达式为:((10 * (6 / ((9 + 3) * -</