struct Solution;
impl Solution {
fn eval_rpn(tokens: Vec<String>) -> i32 {
let mut stack = vec![];
for tok in tokens {
match tok.as_ref() {
"+" => {
let right = stack.pop().unwrap();
let left = stack.pop().unwrap();
stack.push(left + right);
}
"-" => {
let right = stack.pop().unwrap();
let left = stack.pop().unwrap();
stack.push(left - right);
}
"*" => {
let right = stack.pop().unwrap();
let left = stack.pop().unwrap();
stack.push(left * right);
}
"/" => {
let right = stack.pop().unwrap();
let left = stack.pop().unwrap();
stack.push(left / right);
}
_ => {
stack.push(tok.parse::<i32>().unwrap());
}
}
}
stack[0]
}
}
#[test]
fn test() {
let tokens = vec_string!["2", "1", "+", "3", "*"];
let res = 9;
assert_eq!(Solution::eval_rpn(tokens), res);
let tokens = vec_string!["4", "13", "5", "/", "+"];
let res = 6;
assert_eq!(Solution::eval_rpn(tokens), res);
let tokens = vec_string!["10", "6", "9", "3", "+", "-11", "*", "/", "*", "17", "+", "5", "+"];
let res = 22;
assert_eq!(Solution::eval_rpn(tokens), res);
}