improve 2020/01

2020/01/src/main.rs

@@ -1,3 +1,4 @@
+#![feature(bool_to_option)]
 use itertools::Itertools;
 use std::io::BufRead;
 
@@ -10,32 +11,16 @@ fn main() {
     let p1 = input
         .iter()
         .tuple_combinations()
-        .filter(|(&a, &b)| a + b == 2020)
-        .map(|(a, b)| a * b)
-        .next()
+        .find_map(|(&a, &b)| (a + b == 2020).then_some(a * b))
         .unwrap();
     println!("Part 1: {}", p1);
-    /*
-    smol-brain, n³ solution:
-    let p2 = input
-        .tuple_combinations()
-        .filter(|(&a, &b, &c)| a + b + c == 2020)
-        .map(|(a, b, c)| a * b * c)
-        .next()
-        .unwrap();
-    println!("Part 2: {}", p2);
-    */
-    // Ascended n² solution (thanks to Lypheo)
+
     let mut p2_table = vec![None; 2020];
     for (&a, &b) in input.iter().tuple_combinations() {
         if a + b < 2020 {
             p2_table[a + b] = Some((a, b))
         }
     }
-    let (a, b) = input
-        .iter()
-        .filter_map(|x| p2_table[2020 - x])
-        .next()
-        .unwrap();
+    let (a, b) = input.iter().find_map(|x| p2_table[2020 - x]).unwrap();
     println!("Part 2: {}", a * b * (2020 - a - b));
 }