Add day 18

Author: LiquidFun

2020/18/18.rs

@@ -1,50 +1,35 @@
 use std::{collections::HashMap, io::stdin};
 
-use itertools::Itertools;
-
 fn eval(line: &str, plus_precedence: i32) -> i64 {
     let mut nums = Vec::new();
     let mut operators = Vec::new();
-    let precedence = HashMap::from([('(', 10), ('+', plus_precedence), ('*', 1)]);
-    // eprintln!("line = {:?}", line);
+    let precedence = HashMap::from([('(', 0), (')', 0), ('+', plus_precedence), ('*', 1)]);
+
     for c in line.chars().chain(")".chars()) {
-        // eprintln!("c = {:?}, nums = {:?}, ops = {:?}", c, nums, operators);
         match c {
             '0'..='9' => nums.push(c.to_digit(10).unwrap() as i64),
-            '(' =>  operators.push(c),
-            ')' => {
-                while !operators.is_empty() {
+            '(' | '+' | '*' | ')' => { 
+                while !operators.is_empty() && c != '(' {
                     let op = operators.pop().unwrap();
-                    if op == '(' {
+                    if op == '(' && c == ')'  { break }
+                    if precedence.get(&op).unwrap() < precedence.get(&c).unwrap() {
+                        operators.push(op);
                         break;
                     }
                     let func = if op == '*' { |(a, b)| a * b } else { |(a, b)| a + b };
                     let value = nums.pop().zip(nums.pop()).map(func).unwrap();
                     nums.push(value);
                 }
-            }
-            '+' | '*' => {
-                while !operators.is_empty() {
-                    // eprintln!("\tc = {:?}, nums = {:?}, ops = {:?}", c, nums, operators);
-                    let op = operators.last().unwrap();
-                    if *op == '(' || precedence.get(op).unwrap() < precedence.get(&c).unwrap() {
-                        break;
-                    }
-                    let func = if *op == '*' { |(a, b)| a * b } else { |(a, b)| a + b };
-                    let value = nums.pop().zip(nums.pop()).map(func).unwrap();
-                    nums.push(value);
-                    operators.pop();
-                }
-                operators.push(c);
+                if c != ')' { operators.push(c); }
             },
-            _ => (),
+            _ => continue,
         }
     }
     *nums.get(0).unwrap()
 }
 
 fn main() {
-    let lines = stdin() .lines().filter_map(Result::ok).collect_vec();
+    let lines: Vec<String> = stdin() .lines().filter_map(Result::ok).collect();
     println!("{:?}", lines.iter().map(|l| eval(&l, 1)).sum::<i64>()); 
     println!("{:?}", lines.iter().map(|l| eval(&l, 2)).sum::<i64>()); 
-}
+}